“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.”
There are actually two different Greek terms translated into English here with the phrase “men who practice homosexuality”. The first is malakos and the second is arsenokoitai. In recent years repeated attempts have been made to redefine the meanings of these words in order to explain away what the apostle Paul is saying in the clearest possible terms.
Short version: the allegation is that Paul is condemning abusive, coercive or recreational sexual relations between men, but not loving, faithful same-sex relationships.