1 Timothy says (NIV) –
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.
When it refers to “the law” in verse 9, it’s generally thought that the author was referring to religious law. And when it refers to “practising homosexuality” in verse 10, it’s generally thought to be referring to sex between members of the same sex.
This passage is particularly relevant to those who claim that Christians are not obligated to follow any rules other than love – because it tends to imply the opposite of that.
The arguments that gay activists make against this verse, tend to match the arguments they make about 1 Corinthians, but I wont repeat what I wrote about that.