Atheists- do black holes exist?

You realize that many scientists didn't believe in black holes until we found them, right? Relativity doesn't predict that black holes exist, merely what would happen if an object had sufficient mass. It was an extreme case, presented to highlight certain points in the theory, not to suggest that such things existed. The fact that we found them and that they do behave that way Relativity predicts is used as evidence for the theory's accuracy. We can't directly see black holes but we can see when they're pulling stars apart, or the orbits they create for stars in the center of the galaxy.