We have four written accounts of his resurrection, plus at least five accounts, maybe six, of a post-resurrection appearance to multitudes of people. That's pretty impressive for an ancient document. If Jesus really didn't rise from the dead, we would uncover documents that say, "Look guys, he didn't really rise from the dead. Quit lying, guys. I was there, and nothing happened like he said it would." Or you'd see something like "Yeah, I talked to Mary Magdelene, and she says nothing happened, so you guys are all liars." But there's really nothing like that.
You have detailed written sources.
You have eyewitnesses that attested to what happened and could provide details if asked.
We don't have any proof from Christian prosecutors that say he didn't really rise from the dead. Do you realize how easy it would have been to defeat the Christian movement? Just unroll the rock, take the body out, parade it around, and say "You guys fell for his bluff--it's been four days and he's still dead." Why didn't anything like that happen? Don't give me that bogus theory that they "stole the body." Yeah, right. Don't forget the disciples were unsure of Jesus being the Messiah as well. I seriously doubt they would put it all on the line for a guy that apparently got pwned on the cross. Just look at Peter's reaction--he denied any association with the guy, and he was one of the most "faithful" disciples.
That's how the church grew, because there was so many contemporaries that they could talk to to verify the evidence.