Whenever we feel guilty, how can we know whether the Holy Spirit is convicting us or that Satan is accusing us?
Because this is a fallen world, we do nothing from entirely pure motives.
As the prophet Isaiah said:
"All of us have become like one who is unclean, and all our righteous acts are like filthy rags; we all shrivel up like a leaf, and like the wind our sins sweep us away" --Isaiah 64:6
Because our motivations are always imperfect and our choices often difficult, one of Satan's most effective ploys is to confuse and paralyze Christians with his accusations, putting them out of effective action. As our accuser and enemy (1 Timothy 5:14-15; 1 Peter 5:8; Revelation 12:10), Satan delights in our anxiety and fear.
Although we may intellectually accept the premise that no one merits God's grace, Satan knows how to use our emotions to cause us to feel outside of the reach of God's mercy. His accusations are often vague, indefinite, and persistent. They throb like a spiritual migraine. They torment us even after we have acknowledged known wrongs and asked God for forgiveness (1 John 1:9).
Whenever we are overwhelmed by guilt feelings that aren't traceable to a specific sin, or whenever feelings of condemnation persist even after we honestly confess them to the Lord, it is reasonable to assume that we are suffering from false guilt-guilt that is either coming from our own hearts or from our spiritual enemy.
Why can we assume that these feelings of condemnation are not coming from God? The Bible tells us that godly conviction is based on love, not fear. Its purpose is to instruct and to correct, not to torment. The apostle John wrote:
"In this way, love is made complete among us so that we will have confidence on the Day of Judgment, because in this world we are like Him. There is no fear in love. But perfect love drives out fear, because fear has to do with punishment. The one who fears is not made perfect in love." --1 John 4:17-18
God is not arbitrary or cruel. He always convicts His children out of love (2 Samuel 12:13; Luke 15:10). Conviction is His tool to bring us to a deeper reliance upon Christ (2 Corinthians 7:10; Ephesians 2:1-10; 2 Timothy 1:9). His Spirit doesn't overwhelm us with feelings of condemnation for sins that have been confessed and forsaken or for choices that are unavoidably troubling and ambiguous.
When we sin, we will have to live with the consequences of our actions and with the loving correction of the Lord if we do not correct ourselves. Our position as God's children doesn't shield us from responsibility. But the natural consequences of sin will never cause us to lose our family relationship with God or any of the spiritual security that Christ has given us.