By Luke Lancaster
Some Protestant-Christians will say that when Christians are saved, that this is a grace that will never be undone. That would mean that no Christian can go to Hell. To combat this statement, Catholics will point out that there are many Christians who lose their faith or fall into serious sins. Realizing the truth of this, Protestants will argue that such Christians were never Christians to begin with. That way, they can keep their doctrine of eternal security or once-saved-always-saved. To prove this point, they will frequently turn to Matthew 7:21. Let's analyze this text.
In this text, Jesus speaks of Christians who do wonderful things for Christ on earth, such as prophecy in His name, exorcise demons, and perform great works, yet Jesus ultimately will say at the end of time: “I never knew you.” These people saw Jesus as "Lord" and call out to Him as their Lord, yet Jesus rejects them on judgment day. Our Protestant friends will say that such Christians were never Christian to begin with. They never were saved and filled with the Holy Spirit's grace, for Jesus does not say "I used to know you," but "I never knew you." They appeared to on the outside, but inwardly were not changed. Those Christians who have been saved, however, are eternally secure. They cannot fall into mortal sin.
This idea does not really work, though. Take for example a Jewish rabbi’s commentary on the Gospels (Samuel Tobias Lachs, “A Rabbinic Commentary on the New Testament”). He reveals that the phrase “I never knew you” was a typical phrase used by rabbi’s to reject someone that they knew, as a form of ban. He quotes numerous places in the Talmudic literature indicating this. So, to say that Jesus never knew someone, would not mean that they never possessed sanctifying grace. Christians can fall away into mortal sin and lose the Holy Spirit. They are not guaranteed to persevere in godliness.
This is similar to Luke 13:22-30, where Jesus tells the story of a man shutting the door to his house. Those who come and knock on it ask to come in, yet the man inside tells those people that he does not know where they are from. These people are lost for eternity in Hell. They are given this rabbinic ban, and are told the same type of statement as Matthew 7:21 did. Yet, as is the case with such rabbinic bans, the rabbi does know the person in reality. This is clear from Lk. 13:26, where it says that they ate and drank with him, and listened to him preach. They were sent packing because they were evildoers (Lk. 13:27).
As we have seen, Christian’s can lose their salvation, which in the case of Matt. 7, would be if the Christian says “Lord, Lord” but does not do the will of the Father. So prophesying, casting out demons, and doing mighty works are not the only things a Christian has to do. He can do those things and not live a holy life (doing the Father’s will). If they fall into mortal sin, they will lose their relationship with Jesus for eternity.