It is sometimes translated as one who does not believe in God. To me it is a divine flame of Love like all other flames. Only perhaps temporarily trapped in ignorance like most of us, simply because man (Power, Greed) appears to be unkind and a stealer of hope.
Atheists believe in Love and Light; in morals and etiquette... have their own sense of right and wrong and do serve in society, experiencing the same or similar emotions like everyone else. I know many who are excellent models for the way religion should be. Glory be!!