Those who sin deliberately, as a manner of life, don’t belong to God (1Jn 3:9), so as believers we’re already obeying God as best we can (Ps 119:22) and asking Him to help us where we’re powerless to do better. (Ps 119:35) So the sins and faults we’re to purge are often hidden from us: secret faults, where we’re deceived about the way. How do we purge those kinds of sins, those we don’t yet know about?
Our spirit is God’s candle, searching all our inward parts. (Pr 20:27) Since God knows us better than we know ourselves, we can ask Him to take us on a tour of our own hearts (Je 17:10), pointing out secret faults where we need cleansing and healing. (Ps 19:12) We can do this because we’re safe with Him: He loves us infinitely just as we are, with all our brokenness, so there’s no need to be defensive or elusive with Him, even when He’s indignant with us.
With Him inside helping us, we can search our own hearts for hints of secrets faults, looking for clues both in our failings and in the accusations of others. We may be blind to our own sin, but others can generally see them, at least partially. When someone takes the time to blame us for something, or if we can easily see on our own that we’re at fault, let’s despise the shame (Heb 12:2), looking for the underlying belief or character flaw and asking God to deliver, heal and cleanse us. Let’s not fear finding faults in ourselves; let’s fear allowing hidden sin to continue to corrupt our witness, and service for God. (Php 2:12)