You don't have any reason that you have considered. Which is totally fine. The problem comes when atheists believe a priori that any argument for God's existence would be automatically false, even the ones they have never heard or considered.

Your statement suggests there are infinitely many hypotheses that posit "a thing exists, but there is no evidence for it". Then you say others have failed to (properly) consider those hypotheses that you choose to believe. (Which may or not be true, but no evidence either way is evident.)

However, aren't you also saying you are not willing to (properly) consider the infinitely many alternative hypotheses to your own, much less the negation hypothesis of "NOT God"?

Which is better then? To choose to believe in one untestable hypothesis or to believe in none?

A suggestion that there are things you haven't heard of doesn't equate to infinite things. Let's say there are 10 arguments for God's existence, but the only one you are familiar with is "a thing exists, but there is no evidence for it", isn't my statement accurate?

In turn, your statement suggests that all possible ideas about religion for the past thousands of years of human history can be boiled down to a single sentence. You have assumed that everything you don't know about religion is exactly the same as the very little you do know about it. Which one of us is supposed to be close-minded again?

I am willing to consider anything and listen to what anybody has to say. As I said in my post above I went through an atheist period of my own, after all.

No, Atheism doesn't mean that by definition a priori God doesn't exist. That would be wrong indeed, but I never encountered such arguments.

Isn't it right there in the name? a - theism?

No, there is no a priory in there. Others make claims about god and atheists simply say: those are unsubstantiated. That’s all.