Robert Candlish,
Commentary on 1 John “sin should be offensive to me… does it not shock the heavenly instincts of my new-born nature? Do I not feel it now to be beneath me to commit sin? I loathe it, I despise it!”
Love this quote.
Great counsel above.
A few thoughts. I don't want to completely give this a cultural context but John does deal with Gnostics in this Epistle and one of the characteristics of some Gnostics was to have an attitude that what happens in the flesh is not important.
Whether or not he has that particular group in mind, I imagine he has the idea that people feel they have license to sin in mind. If you read Romans 5-8 in succession then it should help you to understand a certain progression of thinking as the assurance of God's favor toward us in the Gospel is developed, in a nutshell, along these lines:
Romans 5: God saves us to the uttermost. If He saved you while He was your enemy do you suppose He will cast you off now that you have been made His friend?
Romans 6: Some might think that if God's grace is manifest in our wickedness that we ought to sin so that grace may abound. God forbid. In fact, I believe this is the tenor of John's admonition. The Apostles teach that those who have been saved have been united to Christ not for licentiousness but for obedience. In sinning, it's not that you are no longer a son but that you are not acting according to the character you have been redeemed to. You're called to remind yourself whose you are.
Romans 7: This war is confirmed in Paul's members who, like us all, knows what he desires to do in his redeemed mind but finds another desire that is battling within. He does the things that he does not want. He knows what is right but does not always do it. Who will deliver him from this body of death? Who will deliver us? Will it be your effort? Will it be your seriousness? Will you earn your way back into being a son again? No! I thank God through Jesus Christ my Lord.
Romans 8: Culminates the point that, though you have many enemies against you - including the devil and his minions that would convince you that you're not worthy of this salvation - in your groaning and your crying out - in your suffering under the weight of sin and struggling against it - do not despair. If you are looking to the Cross, friend, then the Holy Spirit will come alongside of you - your paraclete - and testify to your spirit that you are a Son of God. Indeed, brother, if God has set you upright and has cast His eternal favor upon you and has foreloved you then NOTHING can separate you from the love of God in Christ. If God is for you, friend, then who can be against you.
I urge you, therefore, not to look within for the resources to combat this angst but look again at the perfect Savior. Look again at the great High Priest who made a once-for-all sacrifice for sin and then sat down at the right hand of God and ever lives to intercede for His own. Do you believe in His work? Do you despair of your own ability to approach God apart from His Work? If so, then approach boldly because you have access to grace through the veil of His flesh and you need not doubt the good intentions that God has for you.
Then when you see more clearly what God has done for you in the Gospel will you see more clearly how your reasonable service comes into focus. Never cease striving against sin. Resist it until you sweat. Resist to to point of blood. But don't think your resistance is because you're trying to become acceptable to God. Resist it because you
have been made acceptable by God in Christ Jesus. Resist it because you're an adopted Son who wants to learn how to love His Father. Hate your sin but don't hate that which God has called by name.