In your opinion what causes christians to believe in Jesus

[Angrboda]

Faith in the Bible is an action, which makes it consistent with trust and inconsistent with belief. A belief is something like a proposition that one thinks is true, and nothing more. Even the devils are said to believe, so clearly that's not the source of virtue. In the Bible, every example of faith requires someone to do something: Noah has to build a boat before there's a sign of rain, Peter has to step out into the water, and so on. Every story requires the protagonist to do something in the face of uncertainty, and that something is trusting God.

I think you're talking about works, more properly. Faith is a mental attitude which can be expected, or maybe should be expected, to result in acts. The ancients had rather simplistic ideas about mind and body relationships.