Alma 46:21; “And it came to pass that when Moroni had proclaimed these words, behold, the people came running together with their armor girded about their loins, rending their garments in token, or as a covenant, that they would not forsake the Lord their God; or, in other words, if they should transgress the commandments of God, or fall into transgression, and be ashamed to take upon them the name of Christ, the Lord should rend them even as they had rent their garments.
Leviticus 21:10; “And he that is the high priest among his brethren, upon whose head the anointing oil was poured, and that is consecrated to put on the garments, shall not uncover his head, nor rend his clothes.”
Why would someone (Moroni) who is supposed to be the best representative for God do something that God expressly told the Levites not to do?
All biblical examples of people tearing their clothes was a sign of distress, and not something they would do when making a covenant!
If you continue to read in Alma 46, verses 22 thru 24 give an acceptable explanation of why he used the symbolic action of renting his garment. It was to remind himself and his people to not forget God and to remind them not to fall into transgression or else they would be rent into many pieces, like Joseph’s coat which was rent by his brothers. Also, a remnant of the garment symbolizes that a remnant of Jacob’s seed was PRESERVED, which is what they desired from the Lord, to be preserved against their enemies.
Thus we see that if scriptures are not read and studied with intent to understand they can be taken out of context in obvious yet futile attempt to discredit truth.