Sin is no longer an issue for the believer

"Look, you scoffers,
be astounded and perish;
for I am doing a work in your days,
a work that you will not believe, even if one tells it to you.” (Acts 13:41)

David saw this and prophesied about it:
"Blessed are those whose lawless deeds are forgiven, (the child)
and whose sins are covered; (the young man)
blessed is the man against whom the Lord will not count his sin." (the father) (Rom 4:7-8)

John writes about three levels of maturity in 1 John 2, where each step is a further enlightenment (renewing of the mind) on God’s “to good to be true” work:

I am writing to you, little children, because your sins are forgiven for his name’s sake. (v.12)
What is alarming is that very few, preachers included, know or believe in this amazing truth that all their sins are forgiven.

I am writing to you, young men, because you have overcome the evil one. (v. 13)

The evil one’s principal weapon is condemnation, but the young men has overcome his accusations whatsoever they might do, because their sins are covered.

I am writing to you, fathers, because you know him who is from the beginning. (v. 13)

The fathers have an intimate knowledge of God and know that “Whosoever is born of God doth not commit sin; for his seed remaineth in him: and he cannot sin, because he is born of God.” (1 John 3:9)

Of course, God's "to good to be true" work is much more than this question about sin. It's also about Christ who is our life and His agape love which to a certain degree is almost unfathomable for the human mind, and which defy all human experience.