We are born in sin and we die sinning. That's our fallen nature and we can never be anything but imperfect humans while on this earth.
But Christ has acquitted us of our sins so that we can stand blameless before God. That doesn't mean we don't sin. It means we are saved in spite of our sins.
Christ paid the price for our sins in total, and thus we are covered by His redemption. His innocence becomes our own.
If we assume any responsibility for our own salvation by our good works or righteousness we usurp His sacrifice.
"But by the grace of God I am what I am: and his grace which was bestowed upon me was not in vain; but I laboured more abundantly than they all: yet not I, but the grace of God which was with me." -- 1 Corinthians 15:10
Which merely says that WITHOUT God, I cannot please Him. I can do nothing good unless He abides within me. This doesn't say that our love is covered up by Christ. Paul is merely giving credit to God's Graces, the impetus behind his works of love. Paul is cooperating with God's graces - rather than allowing them to fall without effect.
Regards
We not only diminishing Christ's work on the cross but I would also add that diminishing original sin leads to our failure to fully acknowledging God's sovereignty.