“Examine yourself also by this: When you are tempted, and must decide whether you will serve sin and rush into folly, like a horse into battle, or fight against it and suppress it, what do you say to your soul? ‘Hell will be the end of this course; vengeance will meet with me and find me out!’ It is time for you to look about you; evil lies at the door. Paul’s main argument that sin should not have dominion over believers is that they are ‘not under law, but under grace’ (Romans 6:14). If your battle against sin is only legal principles and motives, what assurance do you have that this sin will not have dominion over you, leading to your ruin?
“Also, this defense will not last long. If your lust has driven you away from stronger gospel considerations, then considerations of law and penalty will speedily fail you also. These will not restrain you when you have voluntarily given up to your enemy a means of preservation a thousand times stronger. Be sure of this, that unless you recover yourself rapidly from this condition, the thing you fear will come upon you. What gospel principles have not done, legal motives cannot do!”
– John Owen, The Mortification of Sin, p.60-61 (italics in original)