If GOD is OMNIPOTENT, God can LIE to US
I think this is the strongest argument against classical theism but let's apply it to islam.
If God is omnipotent and omniscient, he can lie to us and change our reality. So how can we know if everything said in islam (Charia, Paradise for believers) is true?
Let's say, for the sake of argyment, that Islam is true in the sense that a well-defined Allah sent a revelation and laws to Muhammad. What guarantee do I have that I will go to Paradise after following Islam?
Allah could send atheists to Paradise and Muslims to Hell,
Christians to Paradise and others to Hell,
500 pagans to Paradise, 200 Zoroastrians to Hell, and billions into infinite reincarnation. (Why not?)
Or perhaps he created Hell but has never actually sent anyone there. There are infinitely many logical possibilities that contradict your creed like this.
You cannot refute this by saying,
"If everything in our religion is true, then everything will happen as written in our text."
Because your God could modify every aspect of reality, our minds, or even your texts without us ever noticing it. Your creed would have no power against a God capable of doing such things.
So we don't have any rational reason to believe in islam even if islam is true !
Once you realize this, it becomes absurd to submit your life to a God who can do whatever he wants, regardless of what you believe or do.