This is our Lord’s longest and most awesome warning about future punishment. If we are not serving others (v. 35), we may cause others to stumble (“offend,” v. 42); and this might lead to their eternal condemnation. We must deal drastically with sin in our lives, both for our sake and the sake of others, for the fires of hell are real and everlasting. Jesus compared hell to a furnace (Matt. 13:42) and an unquenchable fire. The image here is of the garbage dump in the Valley of Hinnom outside Jerusalem (2 Kings 23:10; Isa. 66:24), where the waste was burned by fire and eaten by worms. The Gk. word for hell (“Gehenna”) comes from the Heb. “ge Hinnom”—the valley of Hinnom. Hell is a real place, and lost souls will suffer there forever. Do we have a love for the lost, or are we only concerned with being “the greatest”? God’s people would indeed be “salted with fire” (suffer persecution—v. 49), and it is important that we “have salt in ourselves”. The believers who read Mark’s Gospel during the “fiery trial” under Nero must have been encouraged by what Jesus said here.