In Alma 14, many women and children were killed because their husbands and fathers believed the words of Alma and Amulek and converted. They were actually thrown into a fire. Amulek was astounded at this and wanted to use the priesthood to stop them (perhaps by some miracle):
“How can we witness this awful scene? Therefore let us stretch forth our hands, and exercise the power of God which is in us, and save them from the flames.” (verse 10)
Alma said that he felt inspired not to intervene because they are automatically saved for their belief in God.
“The Spirit constraineth me that I must not stretch forth mine hand; for behold the Lord receiveth them up unto himself, in glory; and he doth suffer that they may do this thing, or that the people may do this thing unto them, according to the hardness of their hearts, that the judgments which he shall exercise upon them in his wrath may be just; and the blood of the innocent shall stand as a witness against them, yea, and cry mightily against them at the last day.” (verse 11)
The last part of verse 11 was interesting. Another reason Alma gave for not intervening is that “the Lord . . . doth suffer that . . . the people [presumable the ones doing the killing] may do this thing unto them . . . that the judgments which he shall exercise upon them in his wrath may be just”.
So he’s not going to intervene in order that God could punish (exercise judgement upon) them? If Alma and Amulek had intervened and no one was killed, God wouldn’t have needed to punish them. Wouldn’t that have been better all around?
This is about agency. Men have a right to act and be acted upon, and the consequences are then just. God could intervene in pretty much every disaster and save us all from any punishment and the world would be a beautiful Eden, but Lucifer’s plan was rejected long ago.
Alma doesn’t seem to say that it is about agency. He says that it was so God’s punishment would be just.
It does seem to imply that God let those people die in order to justly punish those who did the murdering. I think in this case, we don’t have all the information. Alma could have stopped the crimes from happening, but what would that have accomplished? Would those people who rejected his word earlier have converted or would they have influenced others towards evil later on? We don’t know. but that is my assumption. The Lord used this situation to end their influence, so he could justly take them out, basically.
Maybe Alma did not have time to explain to his recently converted companion the ins and outs of agency, or maybe he did not understand it himself. He only knew the spirit constrained him and that their blood would stand against them at the last day.