The problem of textual corruption for Allah

I have heard  the argument against Christianity that since the nature of YWH is all loving and all powerful  therefore there should be no problem of evil .  I thought of applying the problem of evil against Islam but instead of calling it the problem of evil but the problem of textual corruption.

1. If Allah exists then he is omniscient, omnipotent and his Word is non corruptible 
2. The world contains corrupted words of Allah, I.e the Injill and Torah 
3. If Allah were omniscient, omnipotent and his Word is non corruptible  then the world would not contain corrupt words of Allah.
4.  It is not the case that Allah  exists

Possible way of explaining the problem away, which would open up a can of worms is to claim that Allah was being deceptive when he said non can change his words. And that would open up numerous problems, one would be that Muslims don't have certainty that Allah has perfectly preserved the Quran since his words can be corrupted.  

Secondly a Muslims couldn't argue and say since the Injill and Torah are corrupted they couldn't possibly be the words of Allah, because Allah's words are subject to corruption.