The Bible deals with real life and real people. It tells of people who have messed up big time and yet by the grace of God and the working of the Holy Spirit in them they become heroes of the faith. God sets the highest behavioral standards and gets into the heart of things, including human sexuality. Jesus knows the human heart better than anyone and tells us that sexual sins begin in the thought world. When that world comes under the governance of God, temptation is slain at the source.