In presenting the case for the resurrection of Jesus our first exhibit is often the Gospel accounts.
We have independent traditions, eyewitness accounts, unadorned by later theological sophistication, that give us primary evidence. Those Gospels provide remarkably little detail (Mark 14.51-52), often give a bad press to the first followers (doubting Thomas, Peter the denier), and can sometimes seem hard to reconcile (just how many times did the cock crow when Peter denied Christ?). Actually all this points to their authenticity. Of course, apparent contradictions can be resolved – they are only apparent – but their existence only serves to confirm that we have independent traditions. If four witnesses to a criminal act all gave an identical story then we might suspect collusion!
Before 70 AD
A credible case can be made that the Gospels were originally written sometime before 70 AD. Some scholars date John as late as 90 AD but the gospel itself seems to have been written at a time before the destruction of the Temple in Jerusalem in 70 AD. Unlike the later Gnostic Gospels, the Gospels in your New Testament all demonstrate concern with observational details, names of people and places, along with historical and geographical facts. They are products of the first generation of believers.