Paul warned the Ephesian Christians not to walk as the Gentiles walk. His warning was in regard to their behavior. Christians aren’t supposed to behave or live like those whose lives are characterized by disobedience, both in attitude and action. So in contrast he wrote further —
But you did not learn Christ in this way, if indeed you have heard of Him and have been taught in Him, just as the truth is in Jesus, that in reference to your former manner of life, you lay aside the old self, which is being corrupted in accordance with lusts of deceit, and that you be renewed in the spirit of your mind, and put on the new self, which in the likeness of God has been created in righteousness and holiness of the truth.
The way we live as Christians indicates how we “have learned Christ.” There is a big difference between sitting in a classroom or an auditorium where a subject is being taught and actually “learning” what is being presented. The Ephesian brethren illustrate that for us.
Evidently, some of them had not “learned” the Lord. Paul left Timothy in Ephesus on one occasion to set them straight on some issues (1Timothy 1.3). Earlier in the chapter he felt the need to remind them to walk “worthy” of their calling and to do everything possible “to preserve the unity of the Spirit in the bond of peace.”
How are we doing? Have we “learned” or are we “learning Christ”? The answer to that question is demonstrated in the way we live. Much of learning involves “change.” Christianity calls for “transformed” lives (Romans 12.1-2). How have our lives, our attitudes, and our behavior been “changed for the better”? That’s the mark which determines if we have “learned” Christ.