Revelation 22:18–19 had promised curses upon any Christian who tampers with the Word of God (that is, the book of Revelation). The fullness of those curses will ultimately be imposed upon the sinner by the ultimate Judge when he returns. So awareness of his return becomes incentive to be careful in how we read the Word of God.
20 He who testifies to these things says, “Surely I am coming soon.” Amen. Come, Lord Jesus!