Whereas much of what we know from ancient history is derived from one or two sources, we have no fewer than nine ancient sources, inside and outside the New Testament, corroborating the disciples' conviction that they encountered the resurrected Jesus. That's an avalanche of data.
Lee StrobelPaul said in I Corinthians 15:17, if Christ has not been raised, your faith is futile. So that's the linchpin of the Christian faith, is whether Jesus did indeed, A, live, B, die, and C, was resurrected from the dead, which authenticated his claims of divinity.
Lee Strobel