In your opinion what causes christians to believe in Jesus

[Ravenshire]

If there is no afterlife, there is no point to Christianity.  I wouldn't say it is the only or maion thing, but without it, few people would bother to believe.

Sure, but you're still going to die. The afterlife doesn't resolve anybody's fear of death.

That's fear of dying, not fear of death. The afterlife, were it real, would completely resolve the fear of death, assuming you get to good parts, not the bits where you burn.