Alma 13:3

And this is the manner after which they were ordained, being called and prepared from the foundation of the world, according to the foreknowledge of God, on account of their exceeding faith and good works; in the first place being left to choose good or evil; therefore they having chosen good, and exercising exceeding great faith, are called with a holy calling, yea, with that holy calling which was prepared with, and according to, a preparatory redemption for such;

This is how they were chosen. They were called and prepared from the very beginning of the world. God knew ahead of time they would have great faith and do good things. They were first left to choose between good and evil. Because they chose good and had great faith, they were called with a holy calling. This holy calling was prepared along with a redemption plan for people like them.

Here’s how they were ordained: They were called and prepared before the world even began, according to God’s foreknowledge, because of their deep faith and good works. From the start they were free to choose good or evil. Because they chose good and showed extraordinary faith, they were called with a holy calling—one that was prepared alongside a plan of redemption made just for them.