Credible/Honest Apologetics?

[Mister Agenda]

To be clear, I am a gnostic atheist regarding a God who is both omniscient and omnipotent, as I believe those attributes contradict each other and any God that is supposed to have them is a married bachelor. An omnipotent being can do anything, an omniscient being can only do what it always knew it was going to do. 

The statement " can only do what it always knew it was going to do" is not problematic, and doesn't entail a contradiction with omnipotence, because God doesn't change His intention (because he's omniscient, we only change our mind when we are presented with new information/see the information from a new perspective, but God always has full information and knows all possible perspectives, so he never needs to change his decisions).

I can see why you consider that a good counter, but a fully omniscient being can't even change its mind about which finger to wiggle, that is, it can't even change its mind just to see if it can change its mind. It can't, not even for the most trivial of actions for which information makes no difference. It may not need to change its decisions, but it also can't change its decisions.