I don't think our feelings about God affect it, after all, some atheists treat people better than Christians do.
I think it has more to do with a combination of the other persons attitude, our own levels of energy/ good mood etc and past experience. The last months of working at tech support I was virtually holding my breath when the phone rang, expecting the person at the other end to start screaming at me. That makes it difficult to make the "How may I help" sound cheery