(A verse-by-verse study of First Peter from a NCT perspective.)
1 Peter 1:14-16 As children of obedience who are not conformed to passions formerly in your ignorance, but rather according to the holy one who called you, become holy yourselves in every aspect of life, for the reason that it has been written, "You will be holy, because I Myself am holy."
We (believers) have experienced a new birth which was fathered by God Himself. Therefore, the new family to which we belong is His family. Christians are God's kids. Since this is true, we ought to act like God's kids.
I remember some years ago, as I was well into adult manhood, I noticed myself standing a certain way and leaning a certain way against a door jam while talking with someone. My posture was strangely familiar. I am sure I had stood that way before, but the familiarity ran deeper than that. I wasn't simply observing a repeated pattern in my own life. No, the sense transcended my own behavior. Then is hit me. This is precisely the stance I had seen my father take countless times in my life. He has a unique way of leaning against the door frame when holding a casual conversation with someone in a room. A few days later, my wife observed that I was holding my arm out in a somewhat awkward position and she asked me if that was comfortable. Until she mentioned it, I had no idea I was doing it. It felt fine to me, in fact, it felt extremely natural. And in that moment I realized that in this way, too, I was mimicking my father. Over the next several weeks (and to some degree, even to this day), I began to notice my father manifesting himself in my speech patterns and expressions, and in my sense of humor, and in my attitudes, and in my tendencies. Even my nose is taking on the shape of my dad's nose. This started me thinking about the ways I want to be like him, and the ways I don't (the nose, for example). And it became more and more clear that I resemble my father to a significant degree. Without even trying!
The similarities between a father and son come naturally because of (presumably) genetic legacy, but even more so because of relational legacy. We are most influenced by those with whom we spend the most time. Husbands and wives become increasingly alike over the years (I'm told that they even start to look alike...please pray for my wife) because they spend so much time together. For a son who has had a father in the home, he is going to absorb his dad right into his own ways of thinking and behaving, simply because of their time spent together.
Peter instructs believers to act as children of obedience. If we are God's kids, we ought to behave like Him. The more time we spend with Him, and the more influence He has on us, will result in our looking more and more like Him. In contrast to the natural, inherited, mimicking that I described about me with my dad, we must exert tremendous effort to become like our heavenly Father. It will not come without trying, but only with intentional pursuit of His holy character.
This pursuit is not optional for God's children. We are commanded to be holy according to the holy one who called you. That's a tall order. Consider how God is holy. He is wholly holy. There is no darkness in Him whatsoever (1 John 1:5). God is different from all of His creation, nothing is like Him in all the earth. He is pure righteousness. He is pure perfection. He is flawless and without weakness. He loves with an impeccable love, and judges with absolute justice. He never has a bad day. That is the holiness we are expected to pursue, a holiness that resembles Him.
We do well to remember that He called us. He could have left us to our evil selves only to experience His holy wrath. But, He called us out of darkness into His marvelous light (1 Pet. 2:9-10; Col. 1:13), He adopted us as His children (Rom. 8:14-17), and He judged His only begotten Son in order to give us eternal life with Him. Because of this comprehensive kindness He has shown to us, the only reasonable response is to offer our entire being to Him as a living, holy, sacrifice (Rom. 12:1-2).
Every aspect of life. Not only is it required, it is also universal. We must not be content to have conquered one particular sin, or improved one area of our attitude, or increased our practice of one of the spiritual disciplines. We must press on still more seeking to be altogether like our holy Father in every way. This means that we must never become satisfied with our progress in being different from the world and being like God.
I've heard wives who refuse to submit to their husbands say, "But the Lord knows what I've been through, and he understands why I won't submit. He's okay with me as I am." And husbands who acknowledge their lack of spiritual leadership in the home, but say (and have been saying for years), "Yeah, I probably should give more attention to that. But I'm not going to beat myself up over it. God knows my heart." Or still others who admit their faults so willingly, often in self-deprecating anecdotes, and seem to think that their acknowledgment of the sin makes it all okay. But all of these approaches to sin are unbecoming a child of God. Certainly, our pursuit of holiness must always flow out of the gospel. We strive for perfection, not to be accepted by God, but because we have already been accepted by Him in His beloved Son. Nevertheless, strive we must. We should still mourn our sinfulness and long for righteousness, because we want to be like our heavenly Father and bear His family name in a manner worthy of Him (Eph. 4:1f). God desires this for His people, and He put it in writing: "You will be holy, because I Myself am holy" (Lev. 11:44f; 19:2; 20:7). Let us make it our ambition to do what our Father does, say what He says, love what He loves, and hate what He hates.
Our form ought to take the shape of God, not the passions formerly. Before we became God's children we were children of the devil (1 John 3:7-10). We looked and behaved like him. We pursued the things of our dirty, wicked heart. We had strong desires for our own gratification and pleasure without regard for pleasing God or being kind to others (see Rom. 1:22-32; Eph. 4:17-19).
In your ignorance. As Romans 1:32 makes clear, we were never ignorant of our sin. We liked it, yearned for it, and applauded others who joined in with us. Furthermore, we knew that we deserved the wrath of God because of it. We knew God as righteous judge, and we hated Him for it. But we did not know Him as gentle Father. We were ignorant of His grace. We lacked an experience in our soul of His forgiveness. We had no concept of a close, familial relationship with Him. We did not know Him intimately as a bride knows her husband. In that sense, we were ignorant of our sinfulness and God's righteousness. Now we know, and it changes everything.