The apostle Paul was one of God's most faithful servants. I believe there were three important motivations behind Paul's faithfulness: hope, love and fear.
Paul had a blessed hope of eternal life that motivated him to faithfulness. He also had a great love for Christ. In 2 Corinthians 5:14 he says, "The love of Christ constraineth us," which means it compelled him to remain faithful to God. But Paul's faithfulness also was motivated by something else: the reverential fear of the hour when he would stand before the Judge of the world on judgment day!
Today, the vast majority of Christians possess only the first two motivations. Virtually every believer claims to have the hope of eternal life. And many say in all sincerity, "I know I love Jesus with all my heart."
Yet the truth of a coming day of judgment is the very thing that produces serious, godly believers. Those who put it out of mind are usually cold, careless and indulgent. But the fact remains that, sometime very soon, every person who has ever lived will be gathered to the place of judgment to be judged by Jesus Christ: "For we must all appear before the judgment seat of Christ" (2 Corinthians 5:10). "So then every one of us shall give account of himself to God" (Romans 14:12).
At this very moment, legions of angels stand ready for Jesus' command to gather from the corners of the earth both the wicked and the righteous: "The Son of man shall send forth his angels, and they shall gather out of his kingdom all things that offend, and them which do iniquity" (Matthew 13:41).
All the rich, famous and powerful of all ages will be brought to stand before Him: "And the kings of the earth, and the great men, and the rich men, and the chief captains, and the mighty men . . . hid themselves in the dens and in the rocks of the mountains; and said to the mountains and the rocks, Fall on us, hide us from the face of him that sitteth on the throne, and from the wrath of the Lamb: for the great day of his wrath is come; and who shall be able to stand?" (Revelation 6:15-17).