That's not what it boils down to at all.
What it boils down to is the difference between an external God, and an internal God. Ancient Judaism was all about God as an external absolute, represented by religious laws that no human was allowed to question, or doubt, or disobey. Then Jesus showed up. And Christianity introduced a whole new concept of God: and INTERNAL conception of God, wherein a human being becomes a human manifestation of the divine spirit of God. And with this new internalized God-spirit, alignment with God is no longer being determined by religious laws and absolute obedience, but by one's individual conscience, and the state of one's heart and mind.
The concept of 'sin' changed when this concept of God changed from an external God to an internal God. And Jesus explained it to us. Sin was no longer a matter of breaking some religious law or rule. It became a matter of internal motivation. Just WANTING to break the 'law of love' (for God, ourselves, and each other) became the sin. And sin became a matter of the state of our heart and mind. NOT the defiance of some religious dogma, rules, or laws.
But there are a lot of Christians who really don't like this idea of God being an internalized spirit, and therefor being subjectively experienced and understood. They want God to be the external absolute like in the old testament, that they can use to tell themselves, and everyone else, every minute, what to think and how to behave.
They aren't really Christians, yet. Because they don't trust that God's spirit is within them, and will guide them individually, without the need for all those external religious dogmas and laws and rules. They're just too frightened of being wrong, and untrusting of themselves, to accept an internalized God. They call themselves Christians, but the truth is they haven't been able to get past the old testament idea of God, and accept that God now lives within them. They say the words, but everything they do tells the real story.