Gather all the none believers no. But small groups of them gathering small groups of none believers, perhaps yes. Because as they go into decline, they will become increasingly dominated by the criminal fringe and turn ever more to the dark, then they will start to feel cornered and threatened, not just by none believers, but by still perhaps resurgent religions like Islam and Buddhism. It will be small and mean and pointless, but never underestimate how nasty small and mean and pointless things can get, when fanatics are cornered and don't want to admit to themselves they have lost all the arguments.