Before I descend into this topic, I must warn you, this blog is strictly opinion. There are facts in this post, but I will make no attempt to give references and hence, the scientifically minded of you will just have to look up supporting/condradicting evidence yourself. As for everyone else though, feel free to shamelessly believe my unsubstatiated opinion.
So once upon a time in Ancient Greece some smart bloke (a "philosopher", I believe) came up with an awesome proof of the nonexistence of a benevolent monotheistic god. I'm not sure how much of a prooof it is.
In my opinion the only real proofs out there are mathematical proofs, everything else is just hypothesies with overwhelming supporting evidence, but i digress. But it goes a little something like this (please correct me if i am wrong):
If God is benevolent (good), omnipotent (all powerful) and omniscient (can see everything that is happening) then why is there evil? Does he allow evil to exist despite being able to stop it? Well then he must not be benevolent. If he is unable to to stop evil then he is not omnipotent. etc.
Of course this does not logically disprove the existence of a god, let alone an abrahamic god.
And don't give my that "God had to let evil exist in order to let free will exist" bullshit. If god is omnipotent then he can make a world where evil does not exist but free will does exist. When you are all powerful you can do these things.
Let's examine the christian god for one. There are many occasions in the bible where God boasts of being benevolent and omnipotent, but maybe he was exaggerating or outright lying. Hell, I would if I had godlike powers. If anything, God was quite malevolent in the old testament, he happily smote believers and non-believers alike if they weren't doing what he wanted. Just read the book of Judges if you don't believe me. It was only when he decided to visit earth in human form (Jesus) that God finally understood why his minions weren't constantly doing his bidding,and decided to bring out the benevolent doggie bone and toss it to humanity. He may have died for our sins but we all now the real reason he masterminded his own crucifixion was because he realised just how shit it was being a human.
Well that makes sense. Now if only I could convince a christian to believe their god is not morally infallible...
The other big option is that maybe god is not omnipotent. Sure he may be uber powerful but he doesn't quite have enough power to quash evil and banish it to oblivion. Not whenever he wanted to anyway.
That raises the question of just who or what is stopping god from doing so.
Thankfully, Christian mythology has the answer: Satan.
Only instead of Satan existing because God is letting him exist, Satan exists because God just can't get rid of him.
And this is the concept of dualism. Two eternal beings in a balance/fight for contol of the universe. Sounds a bit like the plot to Constantine. In fact, Dualism is a reccuring theme in pop culture. And each time a movie or book comes out describing the eternal battle between good and evil with God and Lucifer as the respective champions, christians just seem to lap it up. Despite the fact that it inherently goes against their religion. Because in Christian mythology, God is omnipotent so the fight for good would have been won long ago.
Now I do not consider myself a dualist or a monotheist but dualism seems a hell of a lot more feasible than monotheism.