If you want to be certain, you should never get married. You should never change jobs. In fact, you might as well just stay home. Because I don't know anybody who is certain. That need to be certain is just procrastination. ↗
Jesus never said a word about homosexuality. In all of his teachings about multiple things - he never said that gay people should be condemned. I personally think it is very fine for gay people to be married in civil ceremonies. ↗