One must read Matthew 7 in context. Jesus was not talking to the ordinary people, but to the heretical Pharisees. The Pharisees did not originate from Abraham and they did not exist before the period between the Old and New Testaments. It was a heretical Jewish sect that departed from the Torah, and compiled their own version of it with all its complicated and often unworkable laws and rules.
Jesus treated and Pharisees as total heretics, and He told them directly that their father was not Abraham but was the devil. These were the heretics to whom Jesus was speaking. Of course we have modern heretics who have compiled their own gospel based on prosperity, guaranteed healing, positive thinking and self-esteem. Their gospel is all about how their people can become their own gods who can limit God doing anything unless with their permission. These modern "pharisees" give wonderful prophecies that either say nothing, or do not come to pass, they go through the process of casting demons out of people, and they claim to do mighty works for God. But they are into just talk and speech-making, giving motivational speeches, departing from sound doctrine into myths.
These modern religious speech-makers are no different from the Pharisees to whom Jesus spoke in Matthew 7. Both have made up their own version of the Scripturesl, the Pharisees with their rules and regulations, the modern ones with their false gospel.
The Apostle John says that the person who says he has no sin deceives himself and the truth is not in him, but if he confesses his sins, God is faithful and just to forgive his sins and cleanse him from all unrighteousness, and that he who says he has no sin makes God out to be a liar. In the light of that, Jesus will never say, "I never knew you" to anyone who trusts in Him yet struggles with his own sinfulness. He will say to to those who pervert the Gospel and twist His word to teach people myths and unBiblical rules and regulations instead of sound doctrine that points people to Christ.