What the Book of Mormon says about ...

Gentiles (Non-mormons)

They belong to the church and the kingdom of the devil. (If they belong to a non-LDS church.)

There are save two churches only; the one is the church of the Lamb of God, and the other is the church of the devil. 1 Nephi 14:6

For the time speedily shall come that all churches which are built up to get gain, and all those who are built up to get power over the flesh, and those who are built up to become popular in the eyes of the world, and those who seek the lusts of the flesh and the things of the world, and to do all manner of iniquity; yea, in fine, all those who belong to the kingdom of the devil are they who need fear, and tremble, and quake; they are those who must be brought low in the dust; they are those who must be consumed as stubble; and this is according to the words of the prophet. 1 Nephi 22:24