infidelity

Unfaithfulness to a sexual partner, especially a spouse.

An act of sexual unfaithfulness.

Lack of fidelity or loyalty.

Lack of religious belief.

Lack of faith or belief; unbelief; disbelief: with reference to the essential tenets of any religion.

Specifically Disbelief in revealed religion; rejection of the doctrine of inspiration of the Scriptures or of the divine origin of Christianity; or, yet more broadly, disbelief in all forms of religious faith.

Breach of trust; unfaithfulness to a charge or an obligation; dishonesty; disloyalty; deceit: as, the infidelity of a friend or a servant.

Specifically Unfaithfulness to the marriage-vows; adultery.

Lack of faith or belief in some religious system; especially, a lack of faith in, or disbelief of, the inspiration of the Scriptures, of the divine origin of Christianity.