Some good responses to the last post - check out the comments. I agree with a lot of what's there.
I guess I'd say one of the facts that convinces me to take the message of Jesus seriously is this one: the existence across the Roman empire by the end of the first century of small communities of people who believed that Jesus was exclusively the way to experience God.
This is a hard, uncontested fact that demands an explanation for the following reasons
There were lots of cults and religions, philosophies and ways of understanding life in the Roman world. By and large, it was a tolerant culture. providing you bowed the head to the cult of the emperor two or three times a year, you could believe pretty much whatever you liked. And the social expectation was that you'd honour the local gods, the deities of whatever trade you pursued and anything else you chose to.
The amazing thing was that the followers of Jesus were prepared to drop every other faith and worship Jesus exclusively. Only the Jews were similar - but they were a special case because for the most part they were an ethnic group and therefore born that way. The gentile followers of Jesus chose to believe what they did.
And the reason why these early followers of Jesus were prepared to drop all other allegiances - sometimes at great cost to themselves - was because they believed that not only had Jesus lived and died but he had also risen from the dead. More than that, he was alive now and able to bring each believer an experience of God the like of which they'd never had before.
And these people were prepared to die for what they believed - and by the early decades of the second century, this was a relatively common occurrence.
How did a tiny, rural Jewish pressure group, whose leader was executed by the Romans for subverting the state, gain a gentile following in many major cities across the empire? How did it persuade sophisticated gentile people in Corinth and Ephesus, Antioch and even Rome itself, that it held the key to the meaning of life, a key worth surrendering one's life to hang onto?
Because of the resurrection. On the first Easter, the tomb where Jesus had been laid was empty; his disciples saw him, ate with him, listened to him and realised that he was the incarnation of God.
That's the only plausible explanation for the presence of the church in the second quarter of the first century - barely a generation after Jesus' death. And if the resurrection happened, then everything the New Testament says about Jesus is true and worth trusting one's life to.