In your opinion what causes christians to believe in Jesus

[Sheldon]

I already gave my rationale, then again I already gave this unequivocal statement, several times???

I must have missed your rationale.

I doubt that, but one more time then, possibility is not granted a priori, it must be demonstrated.

If you agree it's conceivable, and there’s nothing contradictory or incoherent about it, then wouldn’t it follow that the idea sits—at minimum—within the realm of possibility?

The answer is still no, and the reasons are still the same, I can conceive of mermaids and unicorns, I do not believe they are possible, unless someone can demonstrate them to be so. Why this fact needs repeating over and over is unclear. 

Surely, you consider things possible all the time based on coherence and lack of contradiction—like the possibility of life on other planets. 

It is an objective fact that the existence of a planet where life can emerge and evolve is possible. I live on one, it has nothing to do with what I can conceive of. The probability can be measured scientifically. This is not true of deities, or the supernatural, in the generic sense, which you seem determined to cling to, the claims appear to be unfalsifiable and untestable. 

We don’t need actual objective evidence to accept that it’s not impossible, 

Who is we? I certainly need objective evidence before I believe anything is possible, the double negative is bordering on sophistry, not believing something is possible, is not the same as believing something to be impossible. You'll be telling us that atheism and agnosticism are mutually exclusive next.

It is of course irrational to believe two contradictory claims, it does not however, violate any principle of logic to DISBELIEVE two contradictory claims. This is an error in reasoning I see religious apologists make again and again, I suspect it is often intentional, in order to shift the burden of proof for their claim for an extant deity. Lane Craig has done it in public debates, but he's a clown.