At some point in our lives, we must grow up from our childish ways. Like the Bible says: “When I was a child, I spoke as a child, I understood as a child, I thought as a child; but when I became a man, I put away childish things” (1 Cor 13:11). When we were children we did childish things – we did silly things and acted like…. children. Responsibility in life was far from our thoughts and we lived (what we thought) were happy and carefree lives, not caring or worrying about a thing because typically an adult handled things for us. We could just be who we were and it didn’t matter because it was how a child should be and we had the world by the tail! But then our bodies ‘aged’ into adulthood. There are many of us that while our ‘age’ in years says we are an adult, we still think and act like children. Similarly there are many of us, although we have accepted Christ and claim to be of the ‘saved’ family, we still embrace the ways of our corrupt nature. This corrupt nature is called a man; like the human body, it is of divers parts, supporting and strengthening one another. Sinful desires are deceitful lusts; they promise us happiness, but render us more miserable; and bring us to destruction, if not subdued and mortified. These ways therefore must be put off, as an old garment, a filthy garment; they must be subdued and mortified. Yes, we must GROW UP!
But it is not enough to just shake off corrupt principles; we must move in repentance of them and replace them with gracious ones; putting on the new man. The term “By the new man” is the indication of the new nature, the new creature, directed by a new principle, even regenerating grace, enabling a man to lead a new life seeking in Christ, righteousness and holiness. It’s not an easy thing to do, of course, changing our minds, changing our beliefs, changing our ways — but we don’t have to do it on our own. God will help, if we ask. All we must do is decide we want to change our minds. We will never just BE righteous or holy on our own, but in Him we become these things. As we grow in Him, we become the “new man” (2 Cor 5:17). For the actions we DO take though, the part of growing up that WE must execute: Changing our minds—to align our beliefs with those of God—is one way we step out of our old selves and into our new selves. It’s one way we begin to become the men God intends us to become.
But you have not so learned Christ, if indeed you have heard Him and have been taught by Him, as the truth is in Jesus: that you put off, concerning your former conduct, the old man which grows corrupt according to the deceitful lusts, and be renewed in the spirit of your mind, and that you put on the new man which was created according to God, in true righteousness and holiness (Eph 4:20-24)