The phrase is three words in Greek: ouk (not), egnon (I knew, aorist of ginosko), hymas (you, plural). English renders it flatly as "I never knew you," and the flatness costs the reader the weight the sentence carries in Yeshua's mouth.

Ginosko in Greek covers cognitive knowing, recognition, and acquaintance. Taken alone, "I never knew you" could mean "I never met you." That is not what Yeshua is saying. He is speaking to people who prophesied in His Name, cast out demons in His Name, and did many mighty works in His Name. He met them. He knew them in the acquaintance sense. What He is denying is covenant intimacy, and the register He is operating in is the Hebrew yada, the verb for knowing in the exclusive, embodied, relational sense that Genesis 4:1 and Amos 3:2 carry.

The Septuagint regularly uses ginosko to translate yada, which means the Greek word arrives in the New Testament carrying Hebrew freight. "I never knew you" in Matthew 7:23 is not "we were strangers." It is "we were never in covenant with each other. You used My Name. We were not yada of one another." The whole warning of the passage collapses if the sentence is read as an acquaintance problem. It lands when it is read as a covenant one.