Atheist

1. (n.) One who disbelieves or denies the existence of a God, or supreme intelligent Being.

2. (n.) A godless person.

Thesaurus Entries

Sabbath-breaker, apostate, backslider, blasphemer, deserter, disbeliever, gentile, heathen, infidel, minimifidian, nonbeliever, nullifidian, pagan, recidivist, recreant, renegade, sacrilegist, secularist, unbeliever