Christ (Greek Greek, Ancient (to 1453): Χριστός (Khristós) 'anointed') is a translation of the Hebrew מָשִׁיחַ (Māšîaḥ), the Messiah. The translation appears in the Septuagint version of the Hebrew Bible which predates Christianity by over a century, but in the New Testament it is used to refer to Jesus.
Followers of Jesus became known as Christians (as in Acts 11:26) because they believe Jesus to be the messiah (Christos) prophesied in the Hebrew Bible - therefore they often call him Jesus Christ, meaning Jesus the Christos. The word was originally a title, but later became part of the name "Jesus Christ", yet it is still also used as a title, in the reciprocal use Christ Jesus, meaning "The Messiah Jesus". In common usage—even within secular circles—'Christ' is generally treated as synonymous with "Jesus of Nazareth".
Jesus has never been accepted by most Jews as their Messiah. Many Christians, however, await the Second Coming of Christ when they believe he will fulfill the rest of the Christian Messianic prophecy.
The area of Christian theology which is primarily concerned with the nature and person of Jesus Christ as recorded in the Canonical gospels and the letters of the New Testament is known as Christology.
See also: Holy Name of Jesus.
The word Christ (or similar spellings) appears in English and most European languages, owing to the Greek usage of Christós (transcribed in Latin as Christus) in the New Testament as a description for Jesus. Christ has now become a name, one part of the name "Jesus Christ", but originally it was a title (the Messiah) and not a name; however its use in "Christ Jesus" is a title.  
In the Septuagint version of the Hebrew Bible (written over a century before the time of Jesus), the word Christ was used to translate into Greek the Hebrew mashiach (messiah), meaning "anointed."  Khristós in classical Greek usage could mean covered in oil, or anointed, and is thus a literal translation of messiah.
The spelling Christ (Greek Genitive: Greek, Ancient (to 1453): τοῦ Χριστοῦ, toú Christoú,; Nominative: Greek, Ancient (to 1453): ὁ Χριστὸς, ho Christós) in English was standardized in the 18th century, when, in the spirit of the Enlightenment, the spelling of certain words was changed to fit their Greek or Latin origins. Prior to this, in Old and Middle English, the word was usually spelled Crist the i being pronounced either as, preserved in the names of churches such as St Katherine Cree, or as a short, preserved in the modern pronunciation of Christmas). The spelling "Christ" is attested from the 14th century.
In modern and ancient usage, even within secular terminology, Christ usually refers to Jesus, building on the centuries old tradition of such use. Since the Apostolic Age, the use of the definite article before the word Christ and its development into a proper name signifies its identification with Jesus as the promised Jewish messiah.
At the time of Jesus, there was no single, coherent form or order within Second Temple Judaism, and significant political, social and religious differences existed among the Jews. However, for centuries the Jews had used the term "the Anointed" to refer to their expected deliverer. A large number of Old Testament passages were regarded as messianic by the Jews, many more than are commonly considered messianic by Christians, and various groups of Jews assigned varying degrees of significance to them.
The Greek word Messias appears only twice in the Greek Old Testament of the promised prince (Daniel 9:26; Psalm 2:2); yet, when a name was wanted for the promised one, who was to be at once King and Savior, this title was used.  The New Testament states that the Messiah, long awaited, had come and describes this savior as The Christ. In Matt 16:16 Apostle Peter, in what has become a famous proclamation of faith among Christians since the first century, said, "You are the Christ, the Son of the living God."
The opening words in the Gospel of Mark 1:1, namely "The beginning of the gospel of Jesus Christ, the Son of God" also identify Jesus as both Christ and the Son of God. The divinity being again re-affirmed in Mark 1:11. Thereafter Mark never applies Christ to Jesus as a name. Matthew 1:1 uses Christ as a name and Matthew 1:16 explains it again with: "Jesus, who is called Christ". In the Gospel of John, Jesus refers to himself as the Son of God far more frequently than in the Synoptic Gospels.
The use of the definite article before the word Christ and its gradual development into a proper name show the Christians identified the bearer with the promised Messiah of the Jews who fulfilled all the Messianic predictions in a fuller and a higher sense than had been given them by the Rabbis. In the New Testament e.g. Matthew 1:1, 1:18; Mark 1:1; John 1:17; 17:3; 9:22; Mark 9:40; Luke 2:11; 22:2, the word Christ is preceded by Jesus.
While the Gospels of Mark and Matthew begin by calling Jesus both Christ and Son of God, these are two distinct attributions. They develop in the New Testament along separate paths and have distinct theological implications. The development of both titles involves "the precursor", John the Baptist. At the time in Roman Judaea the Jews had been awaiting the "messiah". And many people were wondering who it would be. When John the Baptist appeared and began preaching, he attracted disciples who assumed he would be announced as the Messiah, or "the one" they had been awaiting. But the title Son of God was not attributed to John.
In the Gospel narrative that describe the life of Jesus, the first instance for him being called the Son of God appears during his Baptism by John the Baptist. In the narrative, a voice from heaven calls Jesus the Son. In Messengers from John the Baptist episode, in Matthew 11:2-6 and Luke 7:18-23. when John the Baptist is in prison two of his disciples go and ask Jesus a question on his behalf: "Are you the one to come after me or shall we wait for another?" indicating that the identity of Jesus as Christ was not yet certain at that time, see also Rejection of Jesus.
In John 11:27 Martha tells Jesus "you are the Christ, the Son of God, who is coming into the world", signifying that both titles were generally accepted (yet considered distinct) among the followers of Jesus before the Raising of Lazarus.
Explicit claims of Jesus being the Messiah are found in the Canonical Gospels in the Confession of Peter (e.g. Matthew 16:16) and the words of Jesus before his judges in the Sanhedrin trial of Jesus.  These incidents involve, of course, far more than a mere claim to the Messiahship; taken in their setting, they constitute a claim to be the Son of God.
In the trial of Jesus before the Sanhedrin and Pilate, it might appear from the narratives of Matthew and Luke that Jesus at first refused a direct reply to the high priest's question: "Art thou the Christ?" Although his answer is given merely as su eipas (thou hast said it), the Gospel of Mark states the answer as ego eimi (I am) and there are instances from Jewish literature in which the expression, "thou hast said it", is equivalent to "you are right". The Messianic claim was less significant than the claim to divinity which caused the high priest the horrified accusation of blasphemy and the subsequent calls for the death sentence. Before Pilate on the other hand it was merely the assertion of his royal dignity which gave ground for his condemnation.
In the Pauline Epistles the word Christ is so closely associated with Jesus thatit is apparent that for the Early Christians there is no need to claim that Jesus is Christ, for that is considered widely accepted among them. Hence Paul can use the term Christos with no confusion as to who it refers to, and as in 1Corinthians 4:15 and Romans 12:5 he can use expressions such as "in Christ" to refer to the followers of Jesus. St. Paul proclaims him as the new Adam, who restores through obedience what Adam lost through disobedience. The Pauline Epistles are a source of some key Christological connections, e.g. Ephesians 3:17-19 relates the Love of Christ to the Knowledge of Christ, and considers the Love of Christ as a necessity for knowing him.
There are also implicit claims to being the Christ in the words and actions of Jesus. Episodes in the life of Jesus and statements about what he accomplished during his three-year public ministry are found throughout the New Testament. Core biblical teachings about the person of Jesus Christ may be summarized that Jesus Christ was and forever is fully God (divine) and, in time and history, became fully human, uniting his human nature and his divine nature in one divine person.
See also: Pre-existence of Christ, Logos (Christianity) and Nativity of Jesus. There are distinct, and differing, views among Christians regarding the existence of Christ before his conception. A key passage in the New Testament is John 1:1-18 where John 1:17 specifically mentions that "grace and truth came through Jesus Christ." Those who believe in the Trinity, consider Christ a pre-existent divine hypostasis called the Logos or the Word. Other, non-Trinitarian views, question the aspect of personal pre-existence or question the aspect of divinity, or both.
The concept of Christ as Logos derives from John 1:1: "In the beginning was the Word, and the Word was with God, and the Word was God." In the original Greek, Logos (λόγος) is used for "Word," and is often used untranslated. In the Christology of the Logos, Christ is viewed as the Incarnation of the "Divine Logos", i.e. The Word.
Saint Paul viewed the Nativity of Jesus as an event of cosmic significance which by the Incarnation of Christ brought forth a new world of harmony to undo the damage caused by the fall of the first man, Adam. St. Paul's eschatological view of the birth of Jesus as the Christ counter-positions him as ushering in the new world of order that leads to salvation, unlike Adam, whose disobedience caused a rift with God. 
In the 2nd century, with his theory of "recapitulation", Saint Irenaeus connected "Christ the Creator" with "Christ the Savior", relying on Ephesians 1:10 ("when the times reach their fulfillment — to bring unity to all things in heaven and on earth under Christ") to gather together and wrap up the cycle of the Nativity and Resurrection of Christ.
See also: Salvation (Christianity).
In Colossians 1:15-16 Apostle Paul viewed the Nativity of Jesus as an event of cosmic significance which changed the nature of the world by paving the way for salvation.    Christian teachings present the Love of Christ as a basis for his sacrificial act that brought forth salvation. In John 14:31 Jesus explains that his sacrifice was performed so: "that the world may know that I love the Father, and as the Father gave me commandment, even so I do." Ephesians 5:25 then states that: "Christ also loved the church, and gave himself up for it".
In the 2nd century, Church Father Saint Irenaeus expressed his views of salvation as in terms of the imitation of Christ and his theory of "recapitulation". For Irenaeus the imitation of Christ is based on God's plan of salvation, which involved Christ as the second Adam. He viewed the Incarnation as the way in which Christ repaired the damage done by Adam's disobedience. For Irenaeus, salvation was achieved by Christ restoring humanity to the image of God, and he saw the Christian imitation of Christ as a key component on the path to salvation. For Irenaeus Christ succeeded on every point on which Adam failed. Irenaeus drew a number of parallels, e.g. just as in the fall of Adam resulted from the fruit of a tree, Irenaeus saw redemption and salvation as the fruit of another tree: the cross of crucifixion.
Following in the Pauline tradition, in the 5th century Saint Augustine viewed Christ as the mediator pf the New Covenant between God and man and as the conqueror over sin. He viewed Christ as the cause and reason for the reconciliation of man with God after the fall of Adam, and he saw in Christ the path to Christian salvation. Augustine believed that salvation is available to those who are worthy of it, through faith in Christ.
In the 13th century Saint Thomas Aquinas aimed to recapture the teachings of the Church Fathers on the role of the Holy Trinity in the economy of salvation. In Aquinas' view angels and humans were created for salvation from the very beginning. For Acquinas the Passion of Christ poured out the grace of salvation and all its virtues unto humanity.
The focus on human history was an important element of the biblically grounded 16th century theology of John Calvin. Calvin considered the first coming of Christ as the key turning point in human history. He viewed Christ as "the one through whom salvation began" and he saw the completion of Christ's plan of salvation as his death and Resurrection.
See also: Christogram and Chrismon. The use of "Χ," derived from Chi, the Greek alphabet initial, as an abbreviation for Christ (most commonly in the abbreviation "Χmas") is often misinterpreted as a modern secularization of the term. Thus understood, the centuries-old English word Χmas, is actually a shortened form of CHmas, which is, itself, a shortened form for Christmas. Christians are sometimes referred to as "Xians," with the 'X' replacing 'Christ.