If you're serious, there are so many. Here's one of the first results I found in a search, but you can find so much writing on it if you want to, which if you actually believe you're following the "truth" you should look into.
One of the most common fundamental contradiction arguments is the Judeo-Christian god is defined as omniscient and omnipotent, all knowing and all powerful, as well as benevolent. If this is true, why is there evil in the world? He's omnipotent so must have the power to make a world in which it doesn't exist, and he must be aware of whatever will happen in the world he creates, since he's omniscient, and must not want evil to exist since he's benevolent.
These cannot all be true. If they were then he'd create a world that satisfies his goals that does not have evil, which he must be capable of doing if he's omnipotent. If evil must exist to accomplish his goals then he isn't omnipotent. If he can't detect evil will exist then he isn't omniscient. If he wants evil to exist then he isn't benevolent.