Immorality and evil is subjective, so yes, you are correct. All humans act in a way they believe is good, whether most agree or not is up to everyone else. Dictating what is right and wrong is exactly what gets us to a point of corruption down the line, because now you have a "moral high ground" to defend any action. If you reject having a higher king you give yourself agency to parse and decide for yourself what is right and wrong. That can be scary, but ultimately what an individual and human collective decides is right and wrong should be up to them.

History also shows that if something is seen as wrong, it will be attacked, and whatever leads to the best outcome for all will typically win out. Nazism, for example, was set to fail because it's ideological and philosophical foundation is more harmful than helpful for humanity as a whole and was acted out on a zero-sum basis. The values in religion are beautiful because they paint the incentives of cooperation in a digestible way, but they innately exist and don't require a "God" to be true. Humans created that higher class to justify their control over others at scale.

I also think God is a fine thing to believe in; it's most definitely better than the state, politics, materialism, what have you. Whatever encourages unity and cooperation is cool with me; religion just has traits and a history that show it's a corruptable solution.