In your opinion what causes christians to believe in Jesus

[Paleophyte]

Then having no girlfriend would be your relationship status.

Correct, it would be non existent, as in no relationship, no girlfriend would exist. 

I thought it an imperfect analogy, as we know girlfriends can exist, unlike deities, but it's actually not a bad analogy at all.

I was using an example of something that we can all agree exists (I hope) to highlight how not having any entails not being in a relationship. I could have had him in a relationship with his hand, but then I'd have needed to employ amputation to properly get the point across and I viewed that as unkind.