Mo. Rev. Stat. § 492.040: Officer shall adopt mode most binding on conscience, when.

Whenever the court or officer by whom any person is about to be sworn shall be satisfied that such person has any peculiar mode of swearing connected with or in addition to the usual form of administering oaths, which is to him of more solemn and binding obligation, the court or officer shall adopt that mode which shall appear to be most binding on the conscience of the person to be sworn.