Alma is wracked with pain, remembers and calls upon Jesus, and the salvation occurs. Isn’t this teaching us that we need do no more than call upon Jesus and we may be saved from sin? Here, as in most cases, it is dangerous to take a specific example and generalize it without reference to all of the other teachings of the gospel. Jesus is the focal point of Alma’s repentance, which certainly was sincere. In that act of repentance, the forgiveness comes. Note that the effect is that he “could remember my pains no more.”
The process of forgiveness is not the same as the process of salvation or exaltation. Alma’s sins were forgiven, he was released from the chains in which those sins had bound him. This process gives Alma a new start, not a completion. Alma, though now forgiven, but do as all must do after we are baptized, we must begin to walk the path of the gospel, and learn to do and be those things that it requires of us.