Your argument only works when you are assuming god actually exists but then again, you would have to prove a god exists and you haven't. If we assume a god exists, picking the ''best'' religion is still not that good because, first of all, how would you ever know, right?
Your question gets us into the domain of truth theory. It is a complex topic.
Unless you are an adherent of philosophical skepticism you accept that objective reality aka truth exists and can be known.
The question we must then answer is how do we know something is true? What non arbitrary criteria or metric do we use to determine truth?
The best answer to this question that I know of is the the Coherence theory of truth. Here is a brief description of what this is.
Coherence Theory of Truth
http://mrhoyestokwebsite.com/Knower/Useful%20Information/Three%20Different%20Theories%20of%20Truth.htm
https://www.perrymarshall.com/articles/religion/godels-incompleteness-theorem/
Gödel proved that there are ALWAYS more things that are true than you can prove.
Any system of logic or numbers that mathematicians ever came up with will always rest on at least a few unprovable assumptions.
Gödel’s Incompleteness Theorem applies not just to math, but to everything that is subject to the laws of logic. Incompleteness is true in math; it’s equally true in science or language or philosophy.
And: If the universe is mathematical and logical, Incompleteness also applies to the universe.
Gödel created his proof by starting with “The Liar’s Paradox” — which is the statement
“I am lying” is self-contradictory, since if it’s true, I’m not a liar, and it’s false; and if it’s false, I am a liar, so it’s true.
So Gödel, in one of the most ingenious moves in the history of math, converted the Liar’s Paradox into a mathematical formula. He proved that any statement requires an external observer.
No statement alone can completely prove itself true.
His Incompleteness Theorem was a devastating blow to the “positivism” of the time. Gödel proved his theorem in black and white and nobody could argue with his logic.
Yet some of his fellow mathematicians went to their graves in denial, believing that somehow or another Gödel must surely be wrong.
He wasn’t wrong. It was really true. There are more things that are true than you can prove.
A “theory of everything” – whether in math, or physics, or philosophy – will never be found. Because it is impossible.
A priori Truth is mathematically inevitable. God is such a Truth. The religious have a more elegant way of summing this up. They call it the necessity of faith.
You ask why can't I prove God? This is the wrong question. The correct question is can I build an integrated and coherent worldview without God? Can I follow the coherence theory of truth and construct a True worldview without God.
Only you can answer that question for yourself. I will tell you, however, that for me the answer was no.
Again more philosophical talk, not something I enjoy. ''a belief is true when it fits in with the set of all our other beliefs without creating a contradiction.'' Ok, if it's so simple, your god is not real. If your god is truly omnipotent and all knowing then why are we here? Oh, right, he gave us free will but then how can he be omnipotent. If we have freewill there is no way for him to know what we are going to do, otherwise it can't be freewill, kind of like: can god create an object so heavy that he can't lift it? The whole idea of god is already contradictory not to mention all the other contradictions mentioned by me before. Like the bible teaching not to kill but pages later saying, kill everyone that works on the sabbath. So I guess I just proved god is not real, right?