What is the religious objection for some health insurance companies not to cover birth control?

Surely no one can be against family planning because it helps reduce abortions and unwanted children. I’m more pro life but I think contraception should be covered 100% and sterilization ( vasectomy and tubal ligation and fallopian tube removal should also be fully covered). I would think if you don’t like abortion you would be for anything to prevent it in the first place. Make sense? But religious right wingers have a problem with contraception being covered too smh!