Contemporary cognitive philosophers define 'belief' as, the psychological state in which one accepts a premise or proposition as being true.
Using that definition, I'd have to say they really believe it.
Using that definition, I'd have to say they really believe it.
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.