Hello Relic, actually, people never stopped sinning since our progenitors' paved the way for the rest of us to do so in the Garden of God, but from the time of their one sin, until the days of Moses
(when the Decalogue and the Law of Moses were finally written), He didn't count people's sins against them ... but people still died anyway ..
Romans 5:12-14.
I wonder why that was so
As far as "worrying" about sin and it's eternal consequences, as a Christian, I no longer do that .. e.g.
John 5:24, 10:27-28. Rather, I worry about dishonoring/displeasing the One who loves me and died in my stead on the Cross to atone for my sins, and to save me from His Father's wrath. I am grieved and feel shame
(like that of an abject failure) whenever I sin, because I know that I've already been freed from my former desire (to sin), since God gave me a
new nature when He saved me .. e.g.
Ezekiel 36:26-27; John 3:3; Ephesians 2:1-5.
Our new nature (or new man/new self) has been given the power to resist the old man/old self/old nature, and we are, in fact, commanded to do just that, by choosing to put on our new self, moment by moment, and to lay aside our old self whenever it rears its ugly head .. e.g.
Ephesians 4:22-24.
You are correct about forgiveness and cleansing, that it is ours, simply for the asking now, because of everything that Jesus did (and continues to do) for us ..
1 John 1:9-2:1.
God bless you!
--Deut