In your opinion what causes christians to believe in Jesus

[John 6IX Breezy]

"Shall not perish, but have everlasting life" is pretty clear, and apparently was thought fairly compelling.

Yes, but John 3:16 is making a spiritual argument. There is no escaping physical death in the Bible—from dust we came and to dust we return. What the Bible does add is a post-death layer, which is heaven or hell. Now, it is definitely the case that the fear of hell does drive some people to Christianity. And Jonathan Edwards' Sinners in the hands of an angry God, is a good example of how some ministers do push on the fear of hell button intentionally. But even then, to say hell drives people to believe in Christianity is odd, since you have to first accept many Christian premises before believing in hell.