According to census data from the 2000 Census, Maine had about 283,024 Roman Catholics and an estimated 8,290 Jews. The leading Protestant denominations were the United Methodist Church, with 31,689 adherents; the United Church of Christ, 29,122; and the American Baptists USA, 26,259. The Muslim community had about 800 members.

Over 800,000 people (about 63.6% of the population) were not counted as members of any religious organization.