The conversion of St. Paul has for long been regarded as weighty evidence for the truth of Christianity

"It is reasonable to believe that the evidence which convinced such a man (St. Paul) of the outandout wrongness of his former course, and led him so decisively to abandon previously cherished beliefs for a movement which he had so vigorously opposed, must have been of a singularly impressive quality. The conversion of Paul has for long been regarded as a weighty evidence for the truth of Christianity. Many have endorsed the conclusion of the eighteenth century statesman George, Lord Lyttelton, that 'the conversion and apostleship of St. Paul alone, duly considered, was of itself a demonstration sufficient to prove Christianity to be a divine revelation.'"

Source: The New Testament Documents: Are They Reliable, 5th edition (1959) by F.F. Bruce, Chapter 6: The Importance of Paul's Evidence, page 37.

Independent non-Christian evidence for the Gospel miracles exists

"If we do proceed to ask what the independent non-Christian evidence for the Gospel miracles is, we shall find that early non-Christian writers who do refer to Jesus at any length do not dispute that He performed miracles. Josephus, as we shall see, calls Him a wonder-worker; later Jewish references in the rabbinical writings, as we shall also see, attribute His miracles to sorcery, but do not deny them, just as some in the days of His flesh attributed His powers to demon possession. Sorcery is also the explanation given by Celsus, the philosophic critic of Christianity in the second century. The early apostles referred to His miracles as facts which their audiences were as well acquainted with as they themselves were; similarly the early apologists refer to them as events beyond dispute by the opponents of Christianity."

Source: The New Testament Documents: Are They Reliable, 5th edition (1959) by F.F. Bruce, Chapter 5: The Gospel Miracles, page 37.

New Testament manuscript attestation is wealthy

"Perhaps we can appreciate how wealthy the New Testament is in manuscript attestation if we compare the textual material for other ancient historical works. For Caesar's Gallic War (composed between 58 and 50 BC) there are several extant manuscripts, but only nine or ten are good, and the oldest is some 900 years later than Caesar's day. Of the 142 books of the Roman History of Livy (59 BC-AD 17) only thirty five survive; these are known to us from not more than twenty manuscripts of any consequence, only one of which, and that containing fragments of Books iii-vi, is as old as the fourth century. Of the fourteen books of the Histories of Tacitus (c. AD 100) only four and a half survive; of the sixteen books of his Annals, ten survive in full and two in part. The text of these extant portions of his two great historical works depends entirely on two manuscripts of the ninth century and one of the eleventh. The extant manuscript of his minor works (Dialogue de Oratoribus, Agricola, Germania) all descend from a codex of the tenth century. The History of Thucydides (c. 460-400 BC) is known to us from eight manuscripts, the earliest belonging to c. AD 900, and a few papyrus scraps, belonging to about the beginning of the Christian era. The same is true of the History of Herodotus (c. 488-428 BC). Yet no classical scholar would listen to an argument that the authenticity of Herodotus or Thucydides is in doubt because the earliest manuscripts of their works which are of any use to us are over 1,300 years later than the originals.

But how different is the situation of the New Testament in this respect!"

- The New Testament Documents: Are They Reliable, 5th edition (1959) by F.F. Bruce, Chapter 1: Does it Matter?, page 8.

The time elapsing between the evangelistic events and the writing of most of the New Testament books is satisfactorily short

"... the time elapsing between the evangelic events and the writing of most of the New Testament books was, from the standpoint of historical research, satisfactorily short.  For in assessing the trustworthiness of ancient historical writings, one of the most important questions is: How soon after the vents took place were they recorded?"

- The New Testament Documents: Are They Reliable, 5th edition (1959) by F.F. Bruce, Chapter 1: Does it Matter?