Alma 24
When the king says “for perhaps, if we should stain our swords again they can no more be washed bright through the blood of the Son of our great God” my reaction is, that’s not how the Atonement works. Repentance is always available. Of course committing murder after what the Anti-Nephi-Lehies had come to know would be difficult to repent of, though I imagine they would easily be forgiven for defending themselves. Later when Mormon points out that those who have been enlightened and then reject the truth of Christ become more hardened I realized how true the words of Anti-Nephi-Lehi were. If they had chosen to shed the blood of their brethren, even in defense, they ran the risk of returning to their previous bloodthirsty ways and they would be more hardened than before.