Men with men and women with women committing what is dishonorable and shameful is not something new under the sun. A debased mind engaging in uncleanness goes back to the early history of mankind. The Old Testament records how God destroyed the cities of Sodom and Gomorrah for the filthy conduct of wicked men who engaged in homosexuality (cf. Genesis 19:4-5; II Peter 2:6-7). In Israel men in the city of Gibeah during the period of the judges engaged in it, too (cf. Judges 19:22-23), and God punished them (chapter 20). It is well known from both Biblical and secular history that homosexuality was practiced in the Greek and Roman cultures. For that reason, the New Testament addressed its sinfulness and called sinners unto repentance – to no longer walk as the Gentile world walked according to licentiousness and uncleanness.
The sin of homosexuality, like adultery, originates in the heart of the individual (cf. Mark 7:21). A person is drawn away by the lusts in his heart. When that unlawful desire conceives, it gives birth to sin (cf. James 1:14-15). The individual decides to act upon a choice aroused by stimulating thoughts and to practice what he finds pleasurable. God condemns both homosexuality and adultery.
The Lord Jesus Christ has proclaimed “that repentance and remission of sins should be preached in His name to all nations” (Luke 24:47). Where sin abounds, grace abounds much more. “Shall we continue in sin that grace may abound? Certainly not! How shall we who died to sin live any longer in it?” (Romans 6:1-2). Forgiveness is available in Christ to all sinners, but He commands that all must repent of sin (cf. Luke 13:3). Some of the Christians in Corinth had been guilty of homosexuality and sodomy, but that was their past because they were washed, sanctified and justified in the name of the Lord (cf. I Corinthians 6:9, 11).