Alma's reply tells us that he had already asked for permission to use the priesthood which they possessed, but the Lord's response tells us volumes about our Heavenly Father. All during the second estate there are millions of times when the free agency of some is exercised in such a way that it causes terrible suffering for others. Satan's plan would not have permitted this. He would have set up a dictatorship and compelled all human beings to avoid evil. But then how would the Father's children learn the difference between good and evil? Without free agency nothing would be learned because no one would be allowed to see the consequences of his or her mistakes.
In fact no mistakes would be allowed under the plan of Satan. For obvious reasons the plan of Satan was rejected. But now consider the consequence of preserving universal free agency under the plan which the family of the gods have always used. Free agency allows some to exercise cruelty and violence. This means there will be victims of cruelty and violence. But what can our Heavenly Father do about it?
To fulfill the probationary purpose of the second estate the Father and even the angels of heaven must endure the agony of beholding the elements of injustice, cruelty and evil up to the point where the evildoers either repent and turn back, or continue to the point where their evil has become infinitely revolting to the entire mass of organized intelligences which serve the Father in this round of his creation.
The Father must wait until these intelligences have reached a point total revulsion against a certain evil before the Father can act. This is because the Father receives his power through the support, honor and obedience of these intelligences.1 The honor and obedience of these intelligences is what makes the universe function under the Father's guidance. But he must not lose their confidence by acting prematurely before these intelligences have reached a unified agreement that will warrant support of the Father when he takes action. If he did so the scripture says the consequences would be catastrophic. He would cease to be God.2
So when Alma asked for permission to stop the burning of the women and children, the Lord explained that their suffering would last but a moment, but at the final judgment these cruel acts would provide the justification for the punishment of these wicked men and the Lord said their suffering would last until they had paid the uttermost farthing. Only when this doctrine is fully understood do we get the significance of Alma's statement in this eleventh verse that God's "wrath must be just." In other words, the intervention by the Father must be justified, and this will not occur until the anger of the intelligences throughout this round of the Father's creation have been so universally aroused that their cup of wrath is filled to overflowing. Then the Father can act. Meanwhile, as the scripture says in Abraham 4:18, the Father is under the necessity of watching and waiting.