Following God's law, we say that it is wrong and sinful. It makes no difference to us who is president or who the arbiters of this law are that sit on the Supreme Court. It is still wrong. It is still a sin. It may be the law of the land, but it is still a sin.
Homosexual activity is sinful.
It is contrary to God's law. Read the first chapter of Paul's letter to the Romans. It will take you about five minutes. Paul says it exactly the way it is. He gives it to you with a bark on.