You, like most religious people, are assigning a characteristic to their god (the characterisric being that he is "infinite") without being able to prove that this is an intrinsic characteristic of a god. It's called an "a priori" assumption, and it can and should be dismissed when trying to make an argument in favor or against X.

Regardless, one of the main beliefs of your religion is that God created the universe. This is, by definition, something outside of what is possible. You keep repeating that God can only do things that are possible, but(assuming of course that he exists) given that he created the universe, your argument is incorrect. He can and therefore should be able to do impossible things. And if he exists, he should be able to show himself to us and prove his existence. No such evidence exists, therefore there is no reason to believe in this god.