One way I reinforce my inveterate functional Pelagianism is by allowing remembrance of a past sin to bring me back into despondency and a renewed plea for forgiveness every time it comes to mind.
The trouble is that (normally) I've asked the Lord to forgive me in the wake of the sin, yet when it comes to mind again I find myself crumpling internally into yet another anguished prayer for forgiveness.
The enemy loves it. He sees I'm not letting a decisive placing of that sin under the blood of Christ settle the issue once and for all. Somehow I allow myself to feel that the more often I ask for forgiveness, and the greater the anguish, the more effectual the blood of Christ on my behalf.
Which is itself works-righteousness. It's a denial that the blood of Christ is enough. It's thinking: I need to help out Christ's work by a super intense, repeated, pleading for that blood. The very gospel application is a gospel denial. My mind pleads grace while my heart self-atones.
Place it under the blood. Once. Then quit asking for forgiveness.
'. . . and the LORD has laid on him the iniquity of us all.' --Isaiah 53:6