Supposing that God were the highest of all possible powers, there is nothing preventing him from being evil and betraying all religions. God can simply redifine the good and the bad depending on what he wants, and make everything good bad, and everything bad turn good. He might even be insane, chosing to baffle his creations with all the wrong advice. If God has to be good because he defines good then there is no good, only stuff he does. And if God happens to torment you and make your existence miserable in every possible way because you preferred yellow over beige, then it is good and just that God decided to torture you, and all human understanding of justice it runs contrary to is false! For if God had to conform to those standards of right and wrong, then that would become a power higher than God. Therefore God has no reason to behave as he does in scripture, nor be subject to any kind of observation. Rationality doesn't apply!
And yet there are fundies who claim God is that much all powerful, yet for some reason, good. Because scripture? Because faith? No. These are not things an omnipotent being is subject to. It is well within the abilities of an omnipotent being such as God to lie to you consistently with scripture and violate your faith, and there would be know way of knowing (unless there's something stopping him that isn't himself, but that would be a kind of power higher than God). What prevents him? The fact that you can imagine worse situations? (Surely that is not the case, since your imagination affects nothing by itself.)
And yet there are fundies who claim God is that much all powerful, yet for some reason, good. Because scripture? Because faith? No. These are not things an omnipotent being is subject to. It is well within the abilities of an omnipotent being such as God to lie to you consistently with scripture and violate your faith, and there would be know way of knowing (unless there's something stopping him that isn't himself, but that would be a kind of power higher than God). What prevents him? The fact that you can imagine worse situations? (Surely that is not the case, since your imagination affects nothing by itself.)