Mormon describes the conflict between Yahweh and the devil. Human beings must choose between the two. Although at times we may be deceived into following the devil, still, the choice to follow Yahweh must be conscious. For those who make a firm decision, the gospel can cut through all of the “snares and the wiles” of the world.
In verse 30, Mormon focuses on the eternal reward of those who faithfully follow Yahweh. Surely he was thinking of the history he will soon record documenting the persecution that befalls believers. He holds up their heavenly goal and heavenly reward that will compensate for the temporal persecutions.
Reference: “Strait and narrow” echoes Matthew 7:14: “Because strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it.” (See commentary accompanying 1 Nephi 8:20 for a discussion of the Book of Mormon’s use of “straight” instead of “strait.”)