I cannot speaks for others, but can speak about my observations.

Christians seem to fear many things, including the declining Christian population, non Christians, non heterosexuals, and other strangers. Fear often leads to aggression, which is like anger.

Atheists seem to accept people in groups who are excluded by Christians. That acceptance seems to say atheists have less fear than Christians; thus, they are less aggressive.

Prison inmates are far more likely to be Christians than atheists, which also suggests atheists are lessangry.

No, but people who care are.