Secularist

n.

1.

One who theoretically rejects every form of religious faith, and every kind of religious worship, and accepts only the facts and influences which are derived from the present life; also, one who believes that education and other matters of civil policy should be managed without the introduction of a religious element.

Noun

1.

secularist - an advocate of secularism; someone who believes that religion should be excluded from government and education

advocate, advocator, exponent, proponent