This pattern is in scripture for a reason. It is intended to be a guide for us as we ask questions such as: Although the priesthood has been conferred upon me, what must I do to obtain power? (D&C 121: 36-37.) It is almost always the case that the priesthood is merely “conferred,” and there is no power within it. Through repentance, the powers of heaven are accessed and the priesthood’s power becomes real. Alma is a prime example of this transition from powerless and error-filled pride into repentance and possession of the Spirit of God.
In response to a question about re-baptism and power to perform the ordinance, I would add the following:
Alma was one of the priests of King Noah. In hindsight he knew what he did among them was wicked. (Mosiah 23: 9.) It was in the position as a priest in King Noah’s court that Alma received his priesthood authority. (Mosiah 11: 5.) Unlike his peers, Alma was converted by the message of Abinadi, and was moved to repentance. (Mosiah 17: 1-2.) When he repented, he received from God authority to proceed in using his priesthood. (Mosiah 18: 18.) The moment Alma’s authority was conferred came after he repented, preached righteousness, asked if others were willing to receive baptism, and proceeded to perform the ordinance. It was at that moment Alma received power through the Spirit. (Mosiah 18: 10-14.)