Irreligion, irreligiousness, or nonreligion is an umbrella term which, depending on context, may be understood as referring to atheism, agnosticism, deism, skepticism, freethought, secular humanism, general secularism, or heresy.

the quality of not being devout

The state of being irreligious; lack of religion; impiety.

The principal one of the great faiths of the world.