I’ve been asked about sinless perfectionism, the belief that once someone becomes a Christian, they are no longer capable of sinning. Because they are clothed in the righteousness of Christ, because they are a new creation in Christ, therefore, just as Christ cannot sin, they cannot sin.
This teaching has, at various times, had considerable prominence. There are some branches of Wesleyan, Pentecostal and Keswick thought that teach this. There are several passages of Scripture we can look at that I think make clear this doctrine of sinless perfectionism is incorrect. I believe it to be a false doctrine.