Issac will need more than just guns to take down the king of the gods.
It took 2 really good stabs from the Blade of Olympus (the sword that ended the Great War and brought the reign of Mount Olympus), infused with the powers of the god of war and the king of the gods (drained during the first time Kratos stabbed Zeus in GoW2), beating his face up after his powers were drained from him (and it still took many punches) to kill him
Playing someone who kills people in a video game = Murderer? Playing a Loli in a video game = Pedo? I don't think so.
You guys are mixing up immortal and invincible, immortal only means you live forever or can contain a permanent age. Just like when elves die lord of the rings, invincible means you can't be hurt in any possible way whatsoever. Even in some actual mythologies gods can die, Norse goes especially, in traditional mythology only an immortal can kill another immortal, but that doesn't make them invincible. I love Isaac but he couldn't do nothing.