Question: "Why will not everyone who says, "Lord, Lord," be saved (Matthew 7:21)?"
Answer: In Matthew 5—7 Matthew records Jesus’ Sermon on the Mount. In that historic message, Jesus challenges His listeners to change their minds about how they can be part of His kingdom, saying at one point that not everyone who says, “Lord, Lord,” will be saved (Matthew 7:21). To that point many believed that just by being related to Abraham and Moses and by obeying the Law of Moses they were assured of their place in God’s kingdom. Jesus counters that notion directly.
In Matthew 7:21, Jesus says, “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but only the one who does the will of my Father who is in heaven.” Leading up to this statement, He had explained that His hearers’ righteousness must exceed even the righteousness of those who were most faithfully obeying the outward expressions of the Law of Moses (Matthew 5:20). He added that righteousness does not come from external obedience to laws and that, by their internal thought violations of those laws, they all were guilty (Matthew 5:21–47). In short, Jesus presented them with a standard they hadn’t considered before: they must be perfect like their heavenly Father is perfect (Matthew 5:48). Of course, living up to that standard is impossible. That is why Jesus proclaimed that people need to repent—to change their minds—about how they could be part of God’s kingdom. They thought they simply needed to be of a certain bloodline and obey a set of laws. Jesus smashed those ideas, pointing them to the actual standard: perfection.
Jesus further explains that the only way to achieve this perfection (since no one can do it on his own) is to have it provided. Ultimately, Jesus would go to the cross to pay for the imperfection of all of us (1 Corinthians 15:1–3) so that by believing in Him we can have life in His name (John 20:31). Jesus was clear—and the apostles after Him—that to be declared righteous by God is to receive grace through faith; righteousness does not come by works or human effort (John 3:16; 6:47; Ephesians 2:8–9).
The recipe is so simple, but we still want to do things our own way. People still want to justify themselves by their own efforts. If we could do that, we would have reason to boast, and we all, it seems, want to have reason to boast in ourselves. In Matthew 7:15–20 Jesus warns His audience about false prophets who will teach deceitfully about righteousness and bear the fruits of that falsehood. Jesus explains that these false prophets can be recognized by their fruits, even if their words are deceptive. Their words may come across as words of righteousness, but they aren’t faithful to the recipe that God provided. In fact, Jesus says, many of them will even call Him “Lord,” but their teachings and their deeds do not align with the will of God. Not everyone who says to Him, “Lord, Lord,” will enter His kingdom (Matthew 7:21). That honor is reserved for those who actually do His will. What is the will of God? That people change their minds (i.e., repent) about how they become righteous before God and come to Him with faith. Without faith it is impossible to please God (Hebrews 11:6).
Simply saying the right things doesn’t grant us God’s righteousness. Not everyone who says to Him, “Lord, Lord,” will enter His kingdom (Matthew 7:21). In Genesis 15:6 we discover that belief in the Lord is credited as righteousness. This is a magnificent and liberating truth. We can’t be perfect on our own, but He is perfect and has sacrificed and paid the penalty so that we can have forgiveness of sin and His righteousness. When we receive these by faith in Him, we are at that moment transferred to His kingdom (Colossians 1:13), and we look forward to the arrival of that kingdom on earth (Colossians 3:1–4).