Belief is a binary mental state. Either you have a belief in something or you don't.
If you have an active belief in the existence of gods, then you are a theist. If you do not have the belief, you are an atheist.
If you have an active belief in the existence of gods, then you are a theist. If you do not have the belief, you are an atheist.
You'd believe if you just opened your heart" is a terrible argument for religion. It's basically saying, "If you bias yourself enough, you can convince yourself that this is true." If religion were true, people wouldn't need faith to believe it -- it would be supported by good evidence.
