Iowa Constitution
Article I - BILL OF RIGHTS.
§ 4 Religious test — witnesses.

No religious test shall be required as a qualification for any office, or public trust, and no person shall be deprived of any of his rights, privileges, or capacities, or disqualified from the performance of any of his public or private duties, or rendered incompetent to give evidence in any court of law or equity, in consequence of his opinions on the subject of religion; and any party to any judicial proceeding shall have the right to use as a witness, or take the testimony of, any other person not disqualified on account of interest, who may be cognizant of any fact material to the case; and parties to suits may be witnesses, as provided by law.

Referred to in Iowa Code §729.1