Irreligion is defined as the absence of religion and/or an indifference towards religion. Sometimes it may also be defined more narrowly as hostility towards religion. The latter definitions - indifference or hostility - mark irreligion as distinct from atheism and theism. A theist may be religious or irreligious; an atheist may also be religious or irreligious. Both atheists and theists may thus be irreligious or not. This definition of irreligion means that it's more of an attitude towards religion rather than an actual religious position.
On a practical level, atheists in contemporary America are more likely than theists to be irreligious in the sense of simply not having religion while both atheists and theists are probably equally likely to be irreligious in the sense of being indifferent to religion. People who are indifferent towards religion are also likely to be indifferent towards belief in gods, known as apatheism. Secularism may track most closely with irreligion; anyone who is irreligious will also be secular.
Tied up in the indictment of Dean's liberalism were related accusations that he was too secular to win in the heartland. In January 2004, the New Republic put Dean on its cover and said that he had a "religion problem." More accurately, Dean could be said to have an irreligion problem: Franklin Foer labeled him as "one of the most secular candidates to run for president in modern history."
- David E. Campbell, "David E. Campbell" in A Matter of faith? Religion in the 2004 presidential election
To avoid discriminating between "religion" and "irreligion," the Supreme Court progressively reinterpreted conscientious objection to include any person whose objection was based on moral or ethical beliefs that were equivalent to traditional religion.
- Encyclopedia of American religion and politics, Paul A. Djupe and Laura R. Olson
Unwilling to accept that a comprehensive toleration in Bayle's sense is possible or desirable, Locke proposes a system of religious toleration capable of accommodating Christian plurality and strengthening freedom of choice in matters of faith--correspondingly weakening both state control over churches and the state church's standing in society--while refusing to accommodate irreligion, unbelief, and libertine lifestyle.
- Jonathan I. Israel, Enlightenment Contested Philosophy, Modernity, and the Emancipation of Man 1670-1752