In your opinion what causes christians to believe in Jesus

[Angrboda]

Always with the armchair psychology lol. Go ahead, tell us what cognitive dissonance is and how it explains the behavior that Boru alleged?

What good are psychological insights if they can't be applied by relatively well-read laypeople?

These days anyone can Google "cognitive dissonance":  "Cognitive dissonance is a state of psychological discomfort experienced when holding conflicting beliefs, attitudes, or behaviors simultaneously. This discomfort motivates individuals to reduce the inconsistency, often by changing their beliefs, attitudes, or behaviors, or by adding new cognitions to justify their actions."

In this case it applies to why religious people, who probably believe in both Christianity and science, seek scientific or at least pseudo-scientific support for their religious beliefs, instead of just dropping one for the other.

Cognitive dissonance in such cases is almost an admission that "something isn't quite right here."  Consistency is an accomplishment which too few people are clever enough to pull off.  
I certainly did not in my own lifetime, so I understand the problem personally.

Given that John's answer as to why people believe was essentially that it was consistent with what they already accepted, I'm not sure how this fits in here.