You are full of shit. You wouldn't have the courage to look into religion which is a huge chunk of the greater philosophy of any civilization. It is a code to live by… a philosophical code.
Not one religion is like another. Not one.
And not all religions offer their host civilizations the best benefits in the way of philosophy with respect to advancing the suitability of the civilization.
Some "religions" have actually killed their civilizations off into extinction, especially those that sacrifice the next generations children.
Other religions are the very reason people survive in large groups after governments and whole empires fail and crash.
And you are correct that without a creator, morality of one man can not be said to be better or worse than another.
Nature knows no justice.
A cat eats a Gazelle, makes no moral difference in nature.
Justice is a man made concept, but, it is a concept that sets man above animal. It is a thing done that gives man the power to raise up even the quality of nature itself, if man chooses wisely.
Now the existence of God is not a matter of philosophy or religion. That is a question of science… reality.. truth.
He either exists or he does not, and nothing you "believe" and no wise saying you can come up with will change that reality.
Pretty cool tho, for people who are not stuffed with self importance illusions of grandeur.
Fact is, any "God" or Creator who could create everything we are looking at, could damn well get a word to his created reading and writing humans, proving his existence beyond a shadow of a doubt as a mathematical statistical reality.
If you weren't so full of yourself, and you actually had the guts to go look at the original Hebrew Greek text that the creator assembled for proof of his existence, with numbers for every letter, and pictograph words for each letter in the alphabet…. If you had the guts to look at the creators math, and science, written long before man could use algebra… you would know there is a creator, and not have to "believe" a damn thing.
But you will not look. You dare not.
Fear that the Creator will be looking right back at you if you do.