Logically atheists have more reasons to be moral than religious people. They know they only got this one life and there is no second chance if they screw it up.
Anyone with a strong belief will occasionally behave in ways that are considered immoral to people not sharing that belief. But as religious people (defined as believing in a god) believe their after life will be much better by behaving according to their own belief, they do not feel obliged to care less about other’s perception of their (immoral) behaviour.
The more religious a person is, the more untrustworthy and potentially dangerous they should be considered as religious fundamentalism defies science and logic.