Most assuredly, neither Jesus' teaching nor His manner of living conformed to this world. His warning is that many will use His name and authority to do marvelous works, but in their personal lives they will not submit to the very instructions that would develop their relationship with God and work to produce His image in them! The only conclusion we can draw is that, despite receiving the instruction, they nonetheless conformed to the world.
Clearly, if we do not know God because we are not really walking in His shoes, as it were, if He does not recognize us or see in us any family resemblance to Him because we are not at one with Him, He will command us to depart, to leave the Marriage Supper! We will not spend eternity with Him. We will have built our house on sandy ground despite all the privileges and warnings given to us!
John W. Ritenbaugh
The Elements of Motivation (Part Two): Vision
These people profess Christ's name. They take it for themselves and do these so-called works, in which they seem to preach, prophesy, do good works like casting out demons, and perform wonders. Yet, what does Jesus say? "I never knew you."
What did they profess? They professed to know God and have a relationship with Him, but He says, "I never knew you, because really you never knew Me." How does He know that? They were practicing lawlessness!
What is lawlessness? Sin! These people lack obedience. They may have the knowledge, but they lack putting this knowledge into godly practice. They believe that they know God's will, but they do not do it. Failing to practice God's will, Jesus says, is sin. Why is failing to practice God's law sin? Because, if we are not doing God's will, we are certainly doing something else!
What is not of God is sin (compare Romans 14:23)!
They have not hit the mark, which is one of the definitions of sin. Obviously, their problems originate in the way they think. If their thoughts were godly, they would behave in a godly manner. However, since they do not behave in a godly manner, their thoughts must not really be godly.
Richard T. Ritenbaugh
Is God in All Our Thoughts?
Many will seek to enter the Kingdom of God but be barred from it because of flagrant sin. Jesus will refuse to answer the knock of unruly sinners who have rejected salvation, though they weep and grind their teeth when they find out they cannot enter God's Kingdom. When the third resurrection arrives, all humanity will have had the opportunity to be saved; everyone's ultimate destiny will have been eternally set. It will be too late for anyone who, after coming to the knowledge of the truth, sins willfully and thereby rejects eternal life. Those who reject God and His way of life must then reap the consequences of that decision - the second death following the third resurrection to judgment.
Martin G. Collins
Basic Doctrines: The Third Resurrection
Other Forerunner Commentary entries containing Matthew 7:21:
1 Corinthians 2:2
1 Corinthians 9:19-22