For the purpose of this commentary, homosexuality refers to any individual engaging in a romantic or sexual relationship with a person of the same biological sex or gender.
Homosexuals and heterosexuals are born with a sinful nature. From this nature, some individuals have a potential susceptibility toward homosexuality versus others who are more vulnerable to other types of sins. Although no one is born gay, everyone is born as a slave to their sinful nature and its insatiable lusts and desires in various forms.
The reason homosexuality (including bisexuality, pansexuality, omnisexuality, lesbianism, etc.) is sinful as an act or lifestyle is because it runs contrary to God’s plan, design, and created order. After God created Adam and Eve, He united them in marriage, made them one flesh, and told them to be fruitful and multiply. These facts, combined with their physical bodies' intricate and intentional design, testify to God’s intention for sex, marriage, procreation, and the family unit.
There is never an instance in Scripture where God approved of or condoned a romantic relationship, sexual act, or marriage between two people of the same biological sex or gender. The only marital union God ever established is between one biological man and one biological woman for a lifetime. Likewise, the only sexual intimacy ordained and blessed by God occurs between a biological man and a biological woman within marriage. Anything outside of those biblical parameters is sinful.
One of the most explicit proofs of God’s disapproval of homosexuality is found in Genesis, chapter 19. God destroyed the cities of Sodom and Gomorrah because they were filled with people committing homosexual acts and orgies. God told Abraham if He found as few as ten righteous people in Sodom, He would spare the entire city for their sake. Given that God brought destruction upon those cities and their inhabitants the following day, it clearly established homosexuality as a sinful, unrighteous lifestyle before God.
A homosexual person is never without hope of breaking free from the cycle of sin and bondage. First, they must acknowledge their sinfulness before God, repent, and trust Jesus for their salvation and redemption. When this occurs, God graciously gives them a new, godly nature and forgives them completely — washing them white as snow. He also sends the Holy Spirit to live inside them to transform them from the inside out. However, if a homosexual person chooses to remain in their sinful state, they will forever be enslaved by their sinful nature and will reap physical and spiritual death in the end.
(See the Scripture References link at the top of the page.)