In Christology, the Logos (Greek: Λόγος, lit. ''Word", "Discourse", or "Reason'') is a name or title of Jesus Christ, derived from the prologue to the Gospel of John (c 100) "In the beginning was the Word, and the Word was with God, and the Word was God", as well as in the Book of Revelation (c 85), "And he was clothed with a vesture dipped in blood: and his name is called The Word of God." These passages have been important for establishing the doctrine of the divinity of Jesus since the earliest days of Christianity.
According to Irenaeus of Lyon (c 130-202) a student of John's disciple Polycarp (c pre-69-156), John the Apostle wrote these words specifically to refute the teachings of Cerinthus, who both resided and taught at Ephesus, the city John settled in following his return from exile on Patmos. Cerinthus believed that the world was created by a power far removed from and ignorant of the Father, and that the Christ descended upon the man Jesus at his baptism, and that strict adherence to the Mosaic Law was absolutely necessary for salvation. Therefore, Irenaeus writes,
The disciple of the Lord therefore desiring to put an end to all such doctrines, and to establish the rule of truth in the Church, that there is one Almighty God, who made all things by His Word, both visible and invisible; showing at the same time, that by the Word, through whom God made the creation, He also bestowed salvation on the men included in the creation; thus commenced His teaching in the Gospel:In the beginning was the Word, and the Word was with God, and the Word was God. The same was in the beginning with God. All things were made by Him, and without Him was nothing made. What was made was life in Him, and the life was the light of men. And the light shines in darkness, and the darkness comprehended it not.
Christian theologians consider John 1:1 to be a central text in their belief that Jesus is God, in connection with the idea that the Father, the Son, and the Holy Spirit together are one God. Although the term Logos or Word is not retained as a title in John's Gospel beyond the prologue, the whole gospel presses these basic claims. As the Logos, Jesus Christ is God in self-revelation (Light) and redemption (Life). He is God to the extent that he can be present to man and knowable to man. The Logos is God,[Jn 1:1] as Thomas stated: "My Lord and my God."[20:28] Yet the Logos is in some sense distinguishable from God, the Father, for "the Logos was with God."[1:1] God and the Logos are not two beings, and yet they are also not simply identical. The paradox that the Logos is God and yet is in some sense distinguishable from God is maintained in the body of the Gospel. That God as he acts and as he is revealed does not "exhaust" God as he is, is reflected in sayings attributed to Jesus: "I and the Father are one"[Jn 10:30] and also, "the Father is greater than I."[14:28] The Logos is God active in creation, revelation, and redemption. Jesus Christ not only gives God's Word to us humans; he is the Word.[1:14] [14:6] The Logos is God, begotten and therefore distinguishable from the Father, but, being God, of the same substance (essence). This was decreed at the First Council of Constantinople (381).
In the context of first and century beliefs, theologian Stephen L. Harris claims that John adapted Philo's concept of the Logos, identifying Jesus as an incarnation of the divine Logos that formed the universe (cf. Proverbs 8:22–36). However, John was not merely adapting Philo's concept of the Logos but defining the Logos, the Son of God, in the context of Christian thought:
Among many verses in the Septuagint prefiguring New Testament usage of the Logos is Psalms 33:6 which relates directly to the Genesis creation. Theophilus of Antioch references the connection in To Autolycus 1:7. Irenaeus of Lyon demonstrates from this passage that the Logos, which is the Son, and Wisdom, which is the Spirit, were present with the Father "anterior to all creation," and by them the Father made all things. Origen of Alexandria likewise sees in it the operation of the Trinity, a mystery intimated beforehand by the Psalmist David. Augustine of Hippo considered that in Ps.33:6 both logos and pneuma were "on the verge of being personified".
τῷ λόγῳ τοῦ κυρίου οἱ οὐρανοὶ ἐστερεώθησαν καὶ τῷ πνεύματι τοῦ στόματος αὐτοῦ πᾶσα ἡ δύναμις αὐτῶν
By the word (logos) of the Lord were the heavens established, and all the host of them by the spirit (pneuma) of his mouth— Psalm 33:6
... just as those who from the beginning (Greek archē) were eyewitnesses and ministers of the word (Greek logos) have delivered them to us.— Luke 1:2 (ESV)
In the beginning was the Word, and the Word was with God, and the Word was God. He was with God in the beginning. Through him all things were made; without him nothing was made that has been made . . . The Word became flesh and made his dwelling among us. We have seen his glory, the glory of the one and only Son, who came from the Father, full of grace and truth.— John 1:1-3, 14 (NIV)
The Gospel of John begins with a Hymn to the Word which identifies Jesus as the Logos and the Logos as divine. The translation of last four words of John 1:1 (θεὸς ἦν ὁ λόγος) has been a particular topic of debate in Western Christianity. This debate mostly centers over the usage of the article ὁ within the clause, where some have argued that the absence of the article before θεὸς, "God," makes it indefinite and should therefore result in the translation, "and the Word was a god". This translation can be found in the Jehovah's Witnesses' New World Translation, and the Unitarian Thomas Belsham's 1808 revision of William Newcome's translation. Others, ignoring the function of the article altogether, have proposed the translation, "and God was the Word," confusing subject and predicate. However, neither translation accurately reflects the role of the article in this type of Greek construction. In this construct, involving an equative verb as well as a predicate nominative in the emphatic position, the article serves to distinguish subject ("the Word") from the predicate ("God"). In such a construction, the predicate, being in the emphatic position, is not to be considered indefinite. As E.C. Colwell observes, "A definite predicate nominative has the article when it follows the verb; it does not have the article when it precedes the verb . . . The absence of the article does not make the predicate indefinite or qualitative when it precedes the verb."
Therefore by far the most common English translation is, "the Word was God," though even more emphatic translations such as "the Word was God Himself" (Amplified Bible) or "the Word ... was truly God" (Contemporary English Version) also exist. Related translations have also been suggested, such as "what God was the Word also was."
Although "Word" is the most common translation of the noun Logos, other less accepted translations have been used, which have more or less fallen by the grammatical wayside as understanding of the Greek language has increased in the Western world. Gordon Clark (1902–1985), for instance, a Calvinist theologian and expert on pre-Socratic philosophy, famously translated Logos as "Logic": "In the beginning was the Logic, and the Logic was with God and the Logic was God." He meant to imply by this translation that the laws of logic were derived from God and formed part of Creation, and were therefore not a secular principle imposed on the Christian world view.
The question of how to translate Logos is also treated in Goethe's Faust, with lead character Heinrich Faust finally opting for die Tat, ("deed/action"). This interpretation owes itself to the Hebrew דָּבָר (Dabhar), which not only means "word," but can also be understood as a deed or thing accomplished: that is, "the word is the highest and noblest function of man and is, for that reason, identical with his action. 'Word' and 'Deed' are thus not two different meanings of Dabhar, but the 'deed' is the consequence of the basic meaning inhering in Dabhar."
It is now generally agreed the concept of the Logos seems to reflect the concept of the Memra (Aramaic for "Word"), a manifestation of God, found in the Targums. Outside of the gospel itself, this connection is perhaps most fully demonstrated in Irenaeus's Demonstration of the Apostolic Preaching, written during the second century.
For a more complete chronological listing of English translations of John, see John 1:1 § John 1:1 in English versions.
That which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked at and our hands have touched—this we proclaim concerning the Word of life.— 1 John 1:1 (NIV)
While John 1:1 is generally considered the first mention of the Logos in the New Testament, chronologically the first reference occurs is in the book of Revelation (c 85). In it the Logos is spoken of as the name of Jesus, who at the Second Coming rides a white horse into the Battle of Armageddon wearing many crowns, and is identified as King of Kings, and Lord of Lords:[19:11-16]
He is clothed with a robe dipped in blood, and His name is called The Word of God . . . And on His robe and on His thigh He has a name written, “KING OF KINGS, AND LORD OF LORDS.”— Revelation 19:13, 16 (NASB)
The first extant Christian reference to the Logos found in writings outside of the Johannine corpus belongs to John's disciple Ignatius (c 35-108), Bishop of Antioch, who in his epistle to the Magnesians, writes, "there is one God, who has manifested Himself by Jesus Christ His Son, who is His eternal Word, not proceeding forth from silence," (i.e., there was not a time when He did not exist). In similar fashion, he speaks to the Ephesians of the Son as "both made and not made; God existing in flesh; true life in death; both of Mary and of God; first passible and then impassible”.
Following John 1, the early Christian apologist Justin Martyr (c 150) identifies Jesus as the Logos. Like Philo, Justin also identified the Logos with the Angel of the LORD, and he also identified the Logos with the many other Theophanies of the Old Testament, and used this as a way of arguing for Christianity to Jews:
I shall give you another testimony, my friends, from the Scriptures, that God begot before all creatures a Beginning, [who was] a certain rational power [proceeding] from Himself, who is called by the Holy Spirit, now the Glory of the Lord, now the Son, again Wisdom, again an Angel, then God, and then Lord and Logos;
In his Dialogue with Trypho, Justin relates how Christians maintain that the Logos,
...is indivisible and inseparable from the Father, just as they say that the light of the sun on earth is indivisible and inseparable from the sun in the heavens; as when it sinks, the light sinks along with it; so the Father, when He chooses, say they, causes His power to spring forth, and when He chooses, He makes it return to Himself . . . And that this power which the prophetic word calls God . . . is not numbered [as different] in name only like the light of the sun but is indeed something numerically distinct, I have discussed briefly in what has gone before; when I asserted that this power was begotten from the Father, by His power and will, but not by abscission, as if the essence of the Father were divided; as all other things partitioned and divided are not the same after as before they were divided: and, for the sake of example, I took the case of fires kindled from a fire, which we see to be distinct from it, and yet that from which many can be kindled is by no means made less, but remains the same.
In his First Apology, Justin used the Stoic concept of the Logos to his advantage as a way of arguing for Christianity to non-Jews. Since a Greek audience would accept this concept, his argument could concentrate on identifying this Logos with Jesus.
Theophilus, the Patriarch of Antioch, (died c 180) likewise, in his Apology to Autolycus, identifies the Logos as the Son of God, who was at one time internal within the Father, but was begotten by the Father before creation:
And first, they taught us with one consent that God made all things out of nothing; for nothing was coeval with God: but He being His own place, and wanting nothing, and existing before the ages, willed to make man by whom He might be known; for him, therefore, He prepared the world. For he that is created is also needy; but he that is uncreated stands in need of nothing. God, then, having His own Word internal within His own bowels, begot Him, emitting Him along with His own wisdom before all things. He had this Word as a helper in the things that were created by Him, and by Him He made all things . . . Not as the poets and writers of myths talk of the sons of gods begotten from intercourse [with women], but as truth expounds, the Word, that always exists, residing within the heart of God. For before anything came into being He had Him as a counsellor, being His own mind and thought. But when God wished to make all that He determined on, He begot this Word, uttered, the first-born of all creation, not Himself being emptied of the Word [Reason], but having begotten Reason, and always conversing with His Reason.
He sees in the text of Psalm 33:6 the operation of the Trinity, following the early practice as identifying the Holy Spirit as the Wisdom (Sophia) of God, when he writes that "God by His own Word and Wisdom made all things; for by His Word were the heavens made, and all the host of them by the Spirit of His mouth" So he expresses in his second letter to Autolycus, "In like manner also the three days which were before the luminaries, are types of the Trinity, of God, and His Word, and His wisdom."
By the third quarter of the second century, persecution had been waged against Christianity in many forms. Because of their denial of the Roman gods, and their refusal to participate in sacrifices of the Imperial cult, Christians were suffering persecution as "atheists." Therefore the early Christian apologist Athenagoras (c 133 – c 190 AD), in his Embassy or Plea to the Emperors Marcus Aurelius and his son Commodus on behalf of Christianity (c 176), makes defense by an expression of the Christian faith against this claim. As a part of this defense, he articulates the doctrine of the Logos, expressing the paradox of the Logos being both "the Son of God" as well as "God the Son," and of the Logos being both the Son of the Father as well as being one with the Father, saying,
Who, then, would not be astonished to hear men called atheists who speak of God the Father, and of God the Son, and of the Holy Spirit, and who declare both their power in union and their distinction in order? . . . the Son of God is the Word [Logos] of the Father, in idea and in operation; for after the pattern of Him and by Him were all things made, the Father and the Son being one. And, the Son being in the Father and the Father in the Son, in oneness and power of spirit, the understanding [Nous] and reason [Logos] of the Father is the Son of God. But if, in your surpassing intelligence, it occurs to you to inquire what is meant by the Son, I will state briefly that He is the first product of the Father, not as having been brought into existence (for from the beginning, God, who is the eternal mind [Nous], had the Word in Himself, being from eternity rational [Logikos]; but inasmuch as He came forth to be the idea and energizing power of all material things, which lay like a nature without attributes, and an inactive earth, the grosser particles being mixed up with the lighter...)
Athenagoras further appeals to the joint rule of the Roman Emperor with his son Commodus, as an illustration of the Father and the Word, his Son, to whom he maintains all things are subjected, saying,
For as all things are subservient to you, father and son, who have received the kingdom from above (for "the king's soul is in the hand of God," says the prophetic Spirit), so to the one God and the Word proceeding from Him, the Son, apprehended by us as inseparable from Him, all things are in like manner subjected.
In this defense he uses terminology common with the philosophies of his day (Nous, Logos, Logikos, Sophia) as a means of making the Christian doctrine relatable to the philosophies of his day.
Irenaeus (c 130-202), a student of the Apostle John's disciple, Polycarp, identifies the Logos as Jesus, by whom all things were made, and who before his incarnation appeared to men in the Theophany, conversing with the ante-Mosaic Patriarchs, with Moses at the burning bush, with Abraham at Mamre, et al., manifesting to them the unseen things of the Father. After these things, the Logos became man and suffered the death of the cross. In his Demonstration of the Apostolic Preaching, Irenaeus defines the second point of the faith, after the Father, as this:
The Word of God, Son of God, Christ Jesus our Lord, who was manifested to the prophets according to the form of their prophesying and according to the method of the dispensation of the Father: through whom all things were made; who also at the end of the times, to complete and gather up all things, was made man among men, visible and tangible, in order to abolish death and show forth life and produce a community of union between God and man.
Irenaeus writes that Logos is and always has been the Son, is uncreated, eternally-coexistent  and one with the Father, to whom the Father spoke at creation saying, "Let us make man." As such, he distinguishes between creature and Creator, so that,
He indeed who made all things can alone, together with His Word, properly be termed God and Lord: but the things which have been made cannot have this term applied to them, neither should they justly assume that appellation which belongs to the Creator 
Again, in his fourth book against heresies, after identifying Christ as the Word, who spoke to Moses at the burning bush, he writes, "Christ Himself, therefore, together with the Father, is the God of the living, who spoke to Moses, and who was manifested to the fathers." 
Post-apostolic Christian writers struggled with the question of the identity of Jesus and the Logos, but the Church’s doctrine never changed that Jesus was the Logos. Each of the first six councils defined Jesus Christ as fully God and fully human, from the First Council of Nicea (325) to the Third Council of Constantinople (680–681). Christianity did not accept the Platonic argument that the spirit is good and the flesh is evil, and that therefore the man Jesus could not be God. Neither did it accept any of the Platonic beliefs that would have made Jesus something less than fully God and fully human at the same time. The original teaching of John’s gospel is, "In the beginning was the Logos, and the Logos was with God, and the Logos was God.... And the Logos became flesh and dwelt among us." The final Christology of Chalcedon (confirmed by Constantinople III) was that Jesus Christ is both God and man, and that these two natures are inseparable, indivisible, unconfused, and unchangeable.
On April 1, 2005, Joseph Cardinal Ratzinger (who became Pope Benedict XVI just over two weeks later) referred to the Christian religion as the religion of the Logos:
Christianity must always remember that it is the religion of the "Logos." It is faith in the "Creator Spiritus," (Creator Spirit), from which proceeds everything that exists. Today, this should be precisely its philosophical strength, in so far as the problem is whether the world comes from the irrational, and reason is not, therefore, other than a "sub-product," on occasion even harmful of its development or whether the world comes from reason, and is, as a consequence, its criterion and goal. The Christian faith inclines toward this second thesis, thus having, from the purely philosophical point of view, really good cards to play, despite the fact that many today consider only the first thesis as the only modern and rational one par excellence. However, a reason that springs from the irrational, and that is, in the final analysis, itself irrational, does not constitute a solution for our problems. Only creative reason, which in the crucified God is manifested as love, can really show us the way. In the so necessary dialogue between secularists and Catholics, we Christians must be very careful to remain faithful to this fundamental line: to live a faith that comes from the "Logos," from creative reason, and that, because of this, is also open to all that is truly rational.
Catholics can use Logos to refer to the moral law written in human hearts. This comes from Jeremiah 31:33 (prophecy of new covenant): "I will write my law on their hearts." St. Justin wrote that those who have not accepted Christ but follow the moral law of their hearts (Logos) follow God, because it is God who has written the moral law in each person's heart. Though man may not explicitly recognize God, he has the spirit of Christ if he follows Jesus' moral laws, written in his heart.
Photinus denied that the Logos as the Wisdom of God had an existence of its own before the birth of Christ. For Socinus, Christ was the Logos, but he denied His pre-existence; He was the Word of God as being His Interpreter (Latin: interpres divinae voluntatis). Nathaniel Lardner and Joseph Priestley considered the Logos a personification of God's wisdom.