God washes, sanctifies, and justifies everyone that trusts in Christ, and they will inherit the kingdom of God. The sexually immoral, idolaters, adulterers, homosexuals—“such were some of you,” says Paul, but a change came “in the name of the Lord Jesus Christ and by the Spirit of our God” (1 Corinthians 6:9–11).
These titles above characterize people who were given over to sexual sin. Even after faith in Christ, people can continue to struggle with these sins. So, just after 1 Corinthians 6:9–11, Paul instructed them further in 1 Corinthians 6:12–20: the body is not for slavery to sexual sin but for the service of the Lord, both now and forever (1 Corinthians 6:12–14); our bodies are members of Christ and not to be party to prostitution (1 Corinthians 6:15–17); we must flee sexual sin lest we sin against ourselves (1 Corinthians 6:18); our bodies are temples of the Spirit bought with the blood of Christ, so we must glorify God therein (1 Corinthians 6:12–20).
In 1 Thessalonians 4:1–8, whereas Paul could have said “such were some of you” (cf. 1 Thessalonians 1:9), the Thessalonian Christians were living pure lives, and Paul simply wanted to encourage them further in their purity. As to how they were “to walk and to please God,” Paul said that “you are doing” these things already (1 Thessalonians 4:1; cf. 4:3–8). However, even Christians who excel in moral purity should remind themselves “to please God… more and more” (1 Thessalonians 4:1). Remember that Judah, Samson, David, and Solomon were believers and yet fell into sexual sin (see Genesis 38; Judges 14, 16; 2 Samuel 11; 1 Kings 11). One can never be too careful.
Paul continues in 1 Thessalonians 4:1–8 to give specific commands concerning God’s will for our sanctification: “that you abstain from sexual immorality”; “that each one of you… control his own body in holiness and honor”; “that no one transgress and wrong his brother in this matter” (1 Thessalonians 4:3b, 4a, 6a). Christians who live this way reflect a saving knowledge of God, avoid the avenging wrath of the Lord, fulfill their purpose in God’s call upon their lives, and show that the Holy Spirit has changed them from the inside out (1 Thessalonians 4:5b, 6b, 7, 8b).
From just two passages above, we have much to encourage us to live sexually pure lives. The Father declares us holy by faith in His Son. Our bodies are given to Christ to serve Him and not our sins. The Spirit lives within, so His holiness should shine without. Lest we fall, we warn ourselves that the Lord will avenge moral misdeeds in His church.
Whatever our sexual sins may have been, the blood of Christ covers them all. Simply come to His cross and be cleansed. And, however much we might excel in moral purity, may God help us to do so more and more.