Today's Gospel reading is from Matthew 7. Jesus told his disciples that only those who does the will of the Father would enter the kingdom of heaven. And to all the others he would say, "I never knew you. Depart from me..."
It would be so terrible for the Lord to not know you. This is worse than being a nobody ~ it's like you have never even existed. So, we must live in such a way as to make him notice us. Another reason for seeking union with him in this life.