The other extreme is to argue that the New Testament is reliable because the New Testament is reliable. The New Testament records that Peter wrote 2 Peter. We must examine the claims that Peter wrote 2 Peter on their merits and not on their face value. One way we can use the comparisons is to examine the sources for all of these works. Historians consider the question of sources to be very important for determining the reliability of a work.
Primary sources are most important of all.
Coins, statues, inscriptions and letters are very valuable. A coin with Domitian on it is excellent evidence that Domitian existed. We have primary letters by Paul and they are excellent evidence about Paul. However, Paul says little about Jesus. If primary sources are not available, and we have no coins, statues, portraits or letters of Jesus, we must look at secondary sources.