True maturity means growing up “into” Christ

^14-16 We are not meant to remain as children at the mercy of every chance wind of teaching and the jockeying of men who are expert in the craft presentation of lies. But we are meant to hold firmly to the truth in love, and to grow up in every way into Christ, the head. For it is from the head that the whole body, as a harmonious structure knit together by the joints with which it is provided, grows by the proper functioning of individual parts to its full maturity in love.

Have no more to do with the old life! Learn the new

^17-19 This is my instruction, then, which I give you from God. Do not live any longer as the Gentiles live. For they live blindfold in a world of illusion, and cut off from the life of God through ignorance and insensitiveness. They have stifled their consciences and then surrendered themselves to sensuality, practising any form of impurity which lust can suggest.