I read the accounts of the miraculous preservation of the Sons of Helaman, and I know there are people today that have that kind of faith. I know of stories from missionaries in the Philippines, groups of youth from my time at EFY, and many families across this broad church that have such faith.
The story of the stripling warriors is not the end of the affair in this chapter. Helaman goes on to share the circumstances of Gid who was given command over the Lamanite prisoners. As Helaman learns the story of Gid, he rejoices even more in the preserving power of the Lord in this their time of war.
There is a footnote at the very end of the chapter that takes me on a bit of journey. Helaman concludes that those who had been slain among the Nephites had entered into the rest of their God. The footnote takes me over to Alma 12, where it very clearly states:
Therefore, whosoever repenteth, and hardeneth not his heart, he shall have claim on mercy through mine Only Begotten Son, unto a remission of his sins; and these shall enter into my rest.Alma 12:34
So the assumed fact in Helaman’s concluding remarks is that those that had died among the Nephites had in fact gone through this process of preparing their souls to enter into the rest of their God.