President Joseph Fielding Smith (1876–1972) explained that Alma had authority to baptize:
“We may conclude that Alma held the priesthood before he, with others, became disturbed with King Noah. Whether this is so or not makes no difference because in the Book of Mosiah it is stated definitely that he had authority [see Mosiah 18:13].
“If he had authority to baptize that is evidence that he had been baptized. Therefore, when Alma baptized himself with Helam that was not a case of Alma baptizing himself, but merely as a token to the Lord of his humility and full repentance” (Answers to Gospel Questions, comp. Joseph Fielding Smith Jr., 5 vols. [1957–66], 3:203).