Theology is not a belief in God. It is a study of the belief in God, the connection between humankind and the possibility of God, and the philosophies grounded in religious doctrine. Saying that trying to understand theology is a waste of time is the same as saying that trying to understand any social science is a waste of time.
You may dismiss the beliefs as “all made up”, but their impact on our world is very real. Is studying politics a waste of time because it’s “all made up”? Or are the arbitrary thoughts and feelings on how the world should be run suddenly more important because we’ve removed a belief that you personally disagree with?
Cynicism is horrible. It is slowly training your brain to always assume the worst in everything and everyone, and has little to do with expectations. Cynicism legitimizes the anger you already feel, and makes it “okay” to yell about it, rather than taking control of your emotions.
You need a philosophy that allows you to take control, not one that justifies your helplessness. Mindfulness practices, and/or existentialist thought eventually leading to positive nihilism can help you.
Edit: After rereading your initial post, I am doubling down on mindfulness practices. The goal of simply not caring doesn’t seem to be helping you, so perhaps it’s best to try and accept and understand your feelings for what they are, rather than attempt to reject them. Your anger is there, and it is real, but it is your choice to act on it, or let it pass. With time, the practice of “letting it pass” will hopefully result in this being the default position. The brain form habits, and if you start to build a habit of letting go, it’ll get easier.