God's forgiveness is complete

I—yes, I alone—am the one who blots out your sins for my own sake and will never think of them again.
Isaiah 43:25 NLT
If we say we have no sin, we are only fooling ourselves and refusing to accept the truth. But if we confess our sins to him, he is faithful and just to forgive us and to cleanse us from every wrong. If we claim we have not sinned, we are calling God a liar and showing that his word has no place in our hearts.
1 John 1:8-10 NLT

The inexcusable bit
"If you had a perfect excuse you would not need forgiveness; if the whole of your action needs forgiveness then there was no excuse for it.
But the trouble is that what we call "asking God's forgiveness" very often really consists in asking God to accept our excuses.
What leads us into this mistake is the fact that there usually is some amount of excuse, some "extenuating circumstances."
We are so very anxious to point these out to God (and to ourselves) that we are apt to forget the really important thing; that is, the bit left over, the bit which the excuses don't cover, the bit which is inexcusable but not, thank God, unforgivable.…
What we have got to take to him is the inexcusable bit, the sin.
We are only wasting time by talking about all the parts which can (we think) be excused.
When you go to a doctor you show him the bit that is wrong—say, a broken arm.
It would be a mere waste of time to keep on explaining that your legs and eyes and throat are all right.
You may be mistaken in thinking so; and anyway, if they are really all right, the doctor will know that.
C. S. Lewis, The Weight of Glory, ""On Forgiveness"" (1947), quoted in The Quotable Lewis by Jerry Root and Wayne Martindale (Tyndale) p 220"