[Serious] Could an omnipotent and omniscient god prove that he was God?

[Objectivist]

No, the argument is that if an omnipotent god wanted us to know it existed and have a relationship with it then we'd know and have a relationship with it.  There would be no such thing as apologetics.  This debate would not exist.  If God wants a planet to break in two then a planet is going to break in two, but somehow getting us all to believe in it is out of it's depth.  A whole bunch of people believe in something that isn't real, it's imaginary, and they want others to believe it with them but they can't, for over 2000 years, present a valid and sound argument to this day.  That's all they need but they don't have it.  This god, if it were real, could just make itself known.  

There are no other kinds of rationality, you either think in accordance with facts and logic or you don't.  You are right, I don't think an omniscient being would have any need for reason guided by logic because it would not need a method of thinking to weed out errors, it would be incapable of errors.  If you want to know what led me away from Christianity, it was the fact that this god supposedly created us with this wonderful, capable brain and then expected us to believe in it based on faith which is nothing more than wishful thinking.  That was the contradiction that led me to start questioning my preacher who had no answer for me but to pat me on the head and tell me to go have some cookies and not think so much.

Most people who profess to be Objectivist are keen to notice logical fallacies. Therefore I find it surprising that your whole post to Bel is basically an argument from incredulity.

Of course, you would be right.  It wasn't an argument so much as an observation of a contradiction.  This god supposedly gave us our brain that works with facts but it says I want you to have faith.  I don't use this contradiction as an argument because I have much better and more fundamental arguments.  But yes, if that were my argument against theism, then it would be an argument from incredulity.