The Greek word translated “the sexually immoral” in the NIV is “pornos”, which literally means a male prostitute.
"Pornos," the masculine noun, used 10x in the NT.
Several feminine nouns are used 37x.
There is no place in the NT where homosexuality is classified as uniquely sinful. In fact, it is usually listed right in there with such common sins as lying.
8 We know that the law is good if one uses it properly. 9 We also know that the law is made not for the righteous but for lawbreakers and rebels, the ungodly and sinful, the unholy and irreligious, for those who kill their fathers or mothers, for murderers, 10 for the sexually immoral, for those practicing homosexuality, for slave traders and liars and perjurers—and for whatever else is contrary to the sound doctrine 11 that conforms to the gospel concerning the glory of the blessed God, which he entrusted to me.
So while the liberal notion that it is not a sin per the Bible, so is the Christian Right's claim that it is The Sin Above All Other Sins. There is very little distinction drawn between homosexual immorality and heterosexual immorality.
But since heterosexual immorality is so widely practiced and accepted, or at least ignored, in today's churches, nobody wants to talk about that. There is something intensely hypocritical about fiercely denouncing a sin one is not tempted to engage in, while practicing or ignoring another sin treated very similarly by the NT.