When persecution of the Christians became extreme, messages were sent to them by church leaders. These messages, usually in the form of letters or public addresses, encouraged the sufferers and advised them concerning the ways in which they should respond to the demands that were being made upon them. Some of these messages are now part of the New Testament. Other letters, several of which have been preserved, were written to counteract false doctrines that arose within the churches. However, these writings were not intended by their respective authors to be regarded as sacred literature comparable to that of the prophets of the Old Testament. Eventually, Christians did come to think of these writings in this way, but the transition from a collection of writings originally designed to meet certain local problems to the status of sacred Scriptures either replacing or else being added to the Old Testament required a comparatively long period of time.
The twenty-seven writings in the New Testament of today were selected from a larger list of writings, and not until the fourth century of our era was any general agreement reached among the Christian churches as to the exact number and selection of writings that should be included. The Gospels and Paul's letters generally were accepted prior to that time, but other writings' inclusion was a matter of serious controversy.
In view of these facts, an adequate understanding of the books in the New Testament cannot be had without some knowledge of the historical background from which they were written, but just how this knowledge can be obtained presents something of a problem. Our chief source of information is the New Testament itself, but there are some references to Jesus and the Christian movement in Roman history and in Jewish literature pertaining to the period in which he lived. However, these non-Christian sources are very meager, and we have good reasons for believing that they are somewhat biased. Christian sources are no doubt biased too, but in the case of both Christian and non-Christian sources, we know the direction in which each of them is biased, and we can make proper allowances. Because only in the Christian sources do we have any detailed account of the life and teachings of Jesus and the general character of the early Christian movement, we need to center our attention on them.
