The key event, and unique claim for Christianity, was that Jesus claimed to be God (God’s Son) and came back to life on the third day after his crucifixion. Without his resurrection, as even the Bible states (1Corth. 15:13-20), Christianity would not exist.
So strong is the historical evidence of the early Christians, and now modern non-Christian or religious skeptics alike… nearly all agree that there were “post-death” appearances of Jesus.
Gerd Ludemann, a leading German critic of the resurrection, said “It may be taken as historically certain that Peter and the disciples had experiences after Jesus death in which Jesus appeared to them as the risen Christ.”
If it is true, the implications are both exciting and serious and it demands a response from everyone.