I tried to tell my late Mother that Jesus died to save us from our sins. She said, "I don't sin." She had had a Bible, an old one with sepia toned pictures, for as long as I could remember. Her Bible had names and birthdates of grandparents in it. Towards the end of her life she she didn't know what had happened to her Bible.
Every person has a conscience that tells them right from wrong. Violating the conscience is to do wrong which is sin. As the write to the Romans put it:
Rom 2:14 for when Gentiles, who do not have the law, by nature do the things in the law, these, although not having the law, are a law to themselves,
Rom 2:15 who show the work of the law written in their hearts, their conscience also bearing witness, and between themselves their thoughts accusing or else excusing them)
One of the problems that comes up everywhere is that usage, custom, and habit lead people and societies to stray from the law of sin. In time their conscience is hardened and sin becomes a part of life. One of the primary purposes of Christianity is to teach people the law and have them turn from sin. It was prophesied long ago:
Isaiah 2:3
He will teach us His ways,
And we shall walk in His paths.”
For out of Zion shall go forth the law,
And the word of the LORD from Jerusalem.
Jesus said to his Apostles:
Mat 28:19 “Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit,
Mat 28:20 “
teaching them to observe all things that I have commanded you; ...
The Apostles carried the law forth from Zion.