Absence of belief in a particular deity, pantheon, or religious doctrine (notwithstanding belief in other deities).
Absence of belief that any deities exist (including absence of the concept of deities).
Rejection of belief that any deities exist (with or without a belief that no deities exist).
Belief that no deities exist (sometimes including rejection of other religious beliefs).
The lack of respect for a god or something sacred.
An impious act.
The state of being impious.