Your argument is that theism is irrational in every way, because it requires belief in it without proof. And that is called "faith" by english speaking people, "iman" by us, have certain words corresponding to it in other languages. You are right. Theism does require faith in all cases. But does it necesserily mean that it is irrational? For something to be irrational, it must oppose your point of view of "rationality". And your point of view of something rational requires scientific proof. But it seems to me that people who do adhere to a god or a number of gods, or just have some sort of belief in the supernatural do not look for scientific proof, although people did, throughout history to scientifically prove god, and did not succeed, and that is why "God" is not a subject of the science of today. Other than creationists who are usually shunned from the scientific point of view for mixing dogma into positive science which does not deal with dogmatic practices, there is no scientist who tries to prove or disprove god.
So why are you looking for some sort of a scientific proof of God? IF the subject is not a part of the branches of science who deal with the phenomena of nature, what kind of a proof can you present?
Also, I mentioned that theists, may they be christian, pagan or jew, do not look for some kind of proof of the validity of their religion and the existence of their God. To them, religion is "rational" and thats why they believe in the religion and the god(s) corresponding to their religion. So what you're trying to do is to disprove their god by using your own perspective of rationality which goes against their point of view of rationality. And this usually does not work, unless the person itself changes his/her point of view of rationality, but until then, anything you fling at them, will usually miss.