John continues his letter by describing the final step of God's wrath at the end of the world. . . . Revelation 16:17-21.
God will save His elect, and we must trust Him to do so, and fulfill our calling as His means to save people, by preaching the gospel. . . . 2 Peter 3:9.
The gospel of Christ can be preached from every book of the Bible--even 2 Peter.