What’s wrong with same-sex ‘marriage’?

Recently I read of a church that fell into serious error. Apparently this happened under the influence of a newly arrived pastor whose predecessor—a godly man—had, for more than three decades, “never preached anything but the gospel truth”. How could this falling away happen so quickly? A friend of the church observed of the former pastor, “He told them the truth all those years. What he didn’t tell them was what wasn’t the truth”.1