In your opinion what causes christians to believe in Jesus

[Sheldon]

Beliefs aren't simply isolated bits of information that one agrees with. They are integrated and predictive mental models of the world.

And so, why do Christians believe in Jesus? For the same reasons anybody believes anything: Because the proposition integrates well within their broader web of beliefs and reduces it's entropy. In other words, because it makes sense to them.

More rubbish

In it's broadest sense, a belief is the affirmation of a claim that something exists, or is true. When we talk about a belief making sense, to me that would have to involve more than a subjective rationalisation. After all a flat earth makes sense to people who believe the earth is flat. 

Now, while an individual is free to set as low a bar for credulity as one wishes, even one that denies objective facts and reality, then they clearly are investing bias, rather than seeking the truth. Existence reflects objective reality, it is in the definition of the word, so to claim something exists, then simultaneously admit it cannot be evidenced in any objectively verifiable way, is too obvious a contradiction for me to lend it any credence.  

Note, this is not, or at least need not, involve me making a contrary claim, as John and countless other religious apologists have tried to claim. Atheism is the lack or absence of belief in any deity or deities, it is literally the absence of theism, and nothing more. Though individuals who happen to be atheists can of course go farther, but I have found that most I have encountered, do not.