Psalm 32:1 and Romans 4:7-8 both say, "Blessed are those whose transgressions are forgiven, whose sins are covered."  The expression 'covering' sins recognises that our sins are permanent statements of our rebellion against God.  They do not evaporate with time or lose their significance as we do more good things.  If we should try to cover up our sins, God sees and knows (Proverbs 28:13a).  But if we confess our sins, and abandon our wicked ways, God will have mercy (Proverbs 28:13) (1 John 1:9).
 
The Bible tells us that those who trust in the sacrifice of Jesus, have their sins 'paid in full'.  John 19:30 says, “Jesus said, ‘It is finished.’ With that, he bowed his head and gave up his spirit.”  The word ‘finished’ means ‘fully paid’.  Although God cannot forget anything, even our sins, He chooses not to remember the sins of those who trust in Jesus’ sacrifice for them (Isaiah 43:25) (Hebrews 10:17).  Therefore, the sins of believers no longer count against them.  The record of our debt to God is cancelled and blotted out.  As with any debt, when it is paid off, the debt is ‘covered’ and we are free.  So although we remain sinners, we are made holy by the blood of Jesus, saved by His grace and fully acceptable to God (Ephesians 1:6).  All this is possible because God has lavished His love upon us (1 John 3:1).

In the same way, we are to love our spiritual siblings.  That marks us out as disciples of Jesus (John 13:34-35).  Such love may even require us to lay down our lives for our believing brothers and sisters (John 15:13).  But more often it requires us to forgive those who sin against us (Matthew 6:14-15), be gentle and longsuffering with those who are annoying or frustrating, and be compassionate and kind to those who do not understand (Colossians 3:12).  The Holy Spirit is at work to teach us how to love the unlovely and to give to people who may never give back to us (Galatians 5:22-26).  Personal purity involves sincere self-giving (1 Peter 1:22).

What do we do with those who sin against us?  Their sin still stands, but we can choose to cover their sin, refuse to bring it to mind and not demand anything from them in compensation - that is love in action.  The word 'deeply' is also used for the taut muscles of runners who are determined to win.  It takes a lot to love sinners like that, but it is the Jesus-way; it certainly cost Him, and it will cost us.  Of course, however much we may love, where there is no repentance there can be no reconciliation.  But love is designed to lead people to repent and be reconciled, as Christ's love has brought us to repentance and back into relationship with Him.