Walk in the Light - Bible Study - Daily Devotionals

Many people believe that by believing in the Lord Jesus their sins are absolved, that they are saved through their faith, and furthermore that once someone is saved they are saved forever, and once the Lord returns they can be raptured and can enter the kingdom of heaven. Yet the Lord Jesus said, "Not every one that said to me, Lord, Lord, shall enter into the kingdom of heaven; but he that does the will of my Father which is in heaven" (Matthew 7:21​). These people who call "Lord, Lord" are all people who have been saved through their faith in the Lord, so why is it that not every one of them can enter the kingdom of heaven? What is going on here? What exactly is the relationship between being saved and entering the kingdom of heaven?