"The church that approves of homosexual relations has by that act ceased to be a true church. Wolfhart Pannenberg"
Piper takes a traditionally selective and apologetic movement through the scriptures to support his claims, starting with Paul's category list of sins in 1 Cor. 6:9-10. Here is Piper's citation of it, including the translation he uses and his italics for emphasis: “Do not be deceived: neither the sexually immoral, nor idolaters, nor adulterers, nor men who practice homosexuality, nor thieves, nor the greedy, nor drunkards, nor revilers, nor swindlers will inherit the kingdom of God."