Throughout the letters of the New Testament, Christians are called lots of things. They are the “elect” (1 Peter 1:1), “faithful brothers” (Colossians 1:2), “beloved” (1 John 2:7), “children of God” (1 John 3:2), a “holy nation” (1 Peter 2:9), and most of all they are called “saints.”
Conspicuously absent from this list is the term “sinners.” There is no place I am aware of where the church, the people of God, are collectively called “sinners.” Moreover, an argument can be made that there is no instance in the New Testament where a believer is referred to as a “sinner.” The closest is Paul’s well-known reference to himself as the “foremost” (or “chief”) of sinners in 1 Timothy 1:15. But the context makes it plain that Paul is using this terminology to refer to his old life as a persecutor of the church. He says, “formerly I was a blasphemer, persecutor, and insolent opponent” (1:13).
Now, of course, this does not mean that Christians do not sin. Indeed, Christians do sin, and sin in ways that are much deeper and more serious than we often realize. This is the whole point of Romans 7 where Paul laments the fact that he often does what he does not want to do. The entire Christian life can be a struggle between the new self and the old self. Paul can even refer to himself as a “wretched man” (Rom 7:24). Therefore we need to renew our minds to what we are in Christ Romans 12:1-3.
As Paul diagnoses his own law-breaking he concludes that whenever he sins, it is not the real Paul that is doing it. He declares, “So now it is no longer I who do it, but sin that dwells within me” (7:17). And again, “Now if I do what I do not want, it is no longer I who do it, but sin that dwells within me” (7:20).
Do not misunderstand what Paul is doing here. He is not trying to conjure up some excuse where he is not guilty of these sins by reason of having a schizophrenic, split personality. No, Paul knows he is culpable for these sins. But, amid doing so, Paul is keen to make it plain that it is not the new Paul that is sinning, but the old Paul. In this sense, he can say that when he sins, he is not his true self.
Put another way, Paul’s identity is bound up in the new man that he has become in Christ. I.e. A New Creation in Christ.
So this explains why Paul refers to believers as “saints” (literally “holy ones”) at the beginning of almost all his letters. Paul is not naïve about the fact that Christians still sin, and sin in major ways (indeed, his letters are often about their sins!). But he wants Christians to think of themselves regarding their new natures, not their old. They are saints who sometimes sin, not sinners who sometimes do right.
And when our true identities are understood rightly, it affects the way we view (and respond to) our sins.
If we instead view ourselves as “saints,” then we will begin to see our sin in a whole new light. If we really are “holy ones” then whatever sins we commit are a deeper, more profound, and more serious departure from God’s calling than we ever realized. Our sin, in a sense, is even more heinous because it is being done by those who now have new natures and a new identity.
We repent because these sins are not ordinary and expected. They are fundamentally contrary to who God has made us to be. It is this tension between our identities and our actions that is lost when we cease to think of ourselves as saints and more importantly as new creations according 2 Corinthians 5:17.