Though some say that the New Testament was written 100-300 years after Christ died, the truth is that it was written before the close of the first century by those who either knew Christ personally, had encountered him, or were under the direction of those who were His disciples.
In the article When were the gospels written and by whom?, I demonstrated that Matthew, Mark, and Luke were all written before 70 A.D. Basically, the book of Acts was written by Luke. But Luke fails to mention the destruction of Jerusalem in 70 A.D., nor does he mention the deaths of James (A.D. 62), Paul (A.D. 64), and Peter (A.D. 65). Since Acts is a historical document dealing with the church, we would naturally expect such important events to be recorded if Acts was written after the fact. Since Acts 1:1-2 mentions that it is the second writing of Luke, the gospel of Luke was written even earlier. Also, Jesus prophesied the destruction of the temple in the gospels: "As for these things which you are looking at, the days will come in which there will not be left one stone upon another which will not be torn down," (Luke 21:6, see also Matt. 24:2; Mark 13:2). Undoubtedly, if Matthew, Mark, and Luke were written after the destruction of the Temple, they would have included the fulfillment of Christ's prophecy in them. Since they don't, it is very strong indication that they were written before 70 A.D.
The gospel of John is supposed to have been written by John the apostle. It is written from the perspective of an eyewitness of the events of Christ's life. The John Rylands papyrus fragment 52 of John's gospel dated in the year 135 contains portions of John 18:31-33, 37-38. This fragment was found in Egypt and a considerable amount of time is needed for the circulation of the gospel before it reached Egypt. It is the last of the gospels and appears to have been written in the 80's to 90's.
Of important note is the lack of mention of the destruction of the Jewish temple in 70 A.D. But this is understandable since John does not mention Jesus' prophecy of the destruction of the Temple. He was not focusing on historical events. Instead, he focused on the theological aspect of the person of Christ and listed His miracles and words that affirmed Christ's deity. This makes perfect sense since he already knew of the previously written gospels.
Furthermore, 1, 2, and 3 John all contain the same writing style as the gospel of John and the book of Revelation which is supposed to have been written in the late 80's or early 90's.
Paul's Writings ~
Romans, 1 & 2 Corinthians, Galatians, Ephesians, Philippians,
Colossians, 1 & 2 Thessalonians, 1 & 2 Timothy, Titus, Philemon
Paul the Apostle was a convert to Christianity. The book of Acts speaks of his conversion in Acts 9. Since Acts was written before 70 A.D. and Paul wrote the Pauline Epistles and we know that Paul died in 64 A.D., the Pauline Epistles were all written before that date. Furthermore, in 1 Cor. 15:3-4 is an early creed of the Christian church where Paul mentions that Jesus had died and risen. "For I delivered to you as of first importance what I also received, that Christ died for our sins according to the Scriptures, 4 and that He was buried, and that He was raised on the third day according to the Scriptures," (1 Cor. 15:3-4). Notice that he says he received this information. From whom did he receive it? Most probably the apostles since he had a lot of interaction with them. This means that Paul received the gospel account from the eyewitnesses. They were, of course contemporaries; they all died before the turn of the century. Therefore, their writings were completed within the lifetime of the apostles of Jesus.
It is not known for sure who wrote the book of Hebrews. Authorship has been proposed for Paul, Barnabas (Acts 4:36), Apollos (Acts 18:24), etc. The only geographical area mentioned is Italy (Heb. 13:24). The latest possible date for the writing of Hebrews is A.D. 95 but could have been written as early as A.D. 67. The book of Hebrews speaks of the sacrifice by the High Priest in the present tense (Heb. 5:1-3; Heb. 7:27) possibly signifying that the destruction of the Jerusalem Temple in 70 A.D. had not yet happened.
This epistles claims to have been written by James, "James, a bond-servant of God and of the Lord Jesus Christ, to the twelve tribes who are dispersed abroad, greetings," (James 1:1). The question is, "Which James?" Is it James, the son of Zebedee (Matt. 10:2-3); James, the son of Alphaeus (Matt. 10:2-3), or the most commonly and accepted James who was the brother of Jesus? "Is not this the carpenter’s son? Is not His mother called Mary, and His brothers, James and Joseph and Simon and Judas? And His sisters, are they not all with us?" (Matt. 13:55,56). Notice that the context of the verses suggest immediate family since it mentions Jesus' Mother, brothers, and sisters. Also, see Gal. 1:18,19 which says "Then three years later I went up to Jerusalem to become acquainted with Cephas, and stayed with him fifteen days. But I did not see any other of the apostles except James, the Lord’s brother." It is probable that James didn't believe in Jesus as the Messiah until Jesus appeared to him after His resurrection as is mentioned in 1 Cor. 15:7, "then He appeared to James, then to all the apostles."
James was martyred by the order of the high priest Ananus after the death of the "procurator Festus in A.D. 61 (Josephus, Ant. 20. 9)." Therefore, the epistle of James was written before A.D. 61.1
1 and 2 Peter
Both epistles clearly state that they were authored by Peter, an eyewitness of Jesus' life and post resurrection appearances. Though there have been some who have doubted the authorship of these two epistles, the clear opening statements of each epistle tell us Peter was the author. "Peter, an apostle of Jesus Christ, to those who reside as aliens, scattered throughout Pontus...", (1 Pet. 1:1) and "Simon Peter, a bond-servant and apostle of Jesus Christ, to those who have received a faith of the same kind as ours..." (2 Pet. 1:1). It certainly seems most logical that Peter is indeed the author of the letters that bear his name.
Peter died in Rome during Nero's persecution of Christians around 64 AD, so the epistles were obviously written before that time.
1, 2, 3 John
The writer of 1 John does not identify himself in the letter. The writer of 2 and 3 John refers to himself as "the elder," (2 John 1; 3 John 1). Regarding the first epistle, authorship can reasonably be determined to be that of John the Apostle. The opening of John is written from the perspective of someone who was there with Jesus (John 1:1-4). Also, "Eusebius (Ecclesiastical History, 3.39) says of Papias, a hearer of John, and a friend of Polycarp, 'He used testimonies from the First Epistle of John. Irenaeus, according to Eusebius (Ecclesiastical History, 5.8), often quoted this Epistle. So in his work Against Heresies (3.15; 5, 8) he quotes from John by name, 1 John 2:18... Clement of Alexandria (Miscellanies, 2.66, p. 464) refers to 1 Jn 5:16, as in John’s larger Epistle.'"2 "In the earliest canonical lists, dating from the end of the second century, 1 John already appears. Indeed, 1 John is quoted as authoritative by Bishop Polycarp of Smyrna [a disciple of John the apostle] before the middle of the second century. The attestation of 2 John is almost as good. There is no second-century reference to 3 John, but that is not surprising, since it deals with a specific, local issue."3 Furthermore, the style of the three epistles is very similar to that of the gospel of John. 1 John mentions the "word of life" (1 John 1:1) as does the gospel of John 1:1, etc.
It appears that the epistles were written after the Gospel of John since the epistles seem to assume a knowledge of the gospel facts.
Date of writing varies from A.D. 60 to the early 90's.4
Jude identifies himself as the brother of James (Jude 1). It is most likely that Jude, in true Christian humility, does not want to equate himself as the brother of Jesus as he is traditionally held to be and seems to be supported by scripture: "Is not this the carpenter’s son? Is not His mother called Mary, and His brothers, James and Joseph and Simon and Judas?" (Matt. 13:55).