Do you have to change your religion?

No, you do not have to change your religion to become a U.S. citizen; the Constitution and federal law guarantee freedom of religion to all persons in the United States. The First Amendment to the Constitution begins "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof," and these protections apply to citizens and non-citizens alike. The naturalization process does not impose any religious test: the Oath of Allegiance can be taken "so help me God" or without that phrase under 8 CFR section 337.1(b), and applicants may swear or affirm the obligation.

Article VI, clause 3 of the Constitution itself prohibits any religious test for any office or public trust under the United States, and federal law extends similar nondiscrimination protections to naturalization through section 311 of the Immigration and Nationality Act, which states that the right to become a naturalized citizen shall not be denied because of race, sex, or marital status. Federal civil rights laws (Title VII of the Civil Rights Act of 1964 in employment, the Fair Housing Act in housing, and others) prohibit religious discrimination in many areas of life.

New citizens may continue to practice any religion or no religion. Conscientious objectors whose religious training and belief prohibits bearing arms may take a modified oath under 8 CFR section 337.1(b) that omits the bear-arms and noncombatant-service clauses, an accommodation that reflects the same constitutional respect for religious freedom. The United States is religiously diverse: every major world religion is represented, and a growing share of Americans identify as having no religious affiliation.