Apostasy vs. Atheism — What's the Difference?

Apostasy (; Greek: ἀποστασία apostasía, "a defection or revolt") is the formal disaffiliation from, abandonment of, or renunciation of a religion by a person. It can also be defined within the broader context of embracing an opinion that is contrary to one's previous religious beliefs.

Atheism, in the broadest sense, is an absence of belief in the existence of deities. Less broadly, atheism is a rejection of the belief that any deities exist.

Abandonment of one's religious faith, a political party, one's principles, or a cause.

Disbelief or lack of belief in the existence of God or gods.

The renunciation of a belief or set of beliefs.

Disbelief in or denial of the existence of God or gods.

Specifically, the renunciation of one's religion or faith.

(narrowly) Belief that no deities exist (sometimes including rejection of other religious beliefs).

An abandonment of what one has voluntarily professed; a total desertion of departure from one's faith, principles, or party; esp., the renunciation of a religious faith; as, Julian's apostasy from Christianity.

(broadly) Rejection of belief that any deities exist (with or without a belief that no deities exist).

The state of having rejected your religious beliefs or your political party or a cause (often in favor of opposing beliefs or causes)

(very broadly) Absence of belief that any deities exist (including absence of the concept of deities).

The act of abandoning a party or cause

(historical) Absence of belief in a particular deity, pantheon, or religious doctrine (notwithstanding belief in other deities).

The disbelief or denial of the existence of a God, or supreme intelligent Being.

Godlessness.

The doctrine or belief that there is no God

A lack of belief in the existence of God or gods