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The concept of being sinless? Or falling into sin at times?
I believe the root of all sin is selfishness. Think about all of the times that you have been tempted to sin. Why were you tempted? Was it something you wanted that you knew was wrong? What something you wanted to do that you knew you shouldn't? Was something that would hurt someone else? Every time I have ever been tempted to sin, it has because of my own selfishness. Every time that I have been tempted to sin, I knew that it could possibly effect my right standing with God and others.
When we love God and others before ourself, it makes it easier to walk away from temptation. If we true feel this way toward God and others then the last thing we want to do is something that might hurt them in some capacity.
Loving God and others helps us die to our sense of self and, as a result, helps us overcome the temptation to sin. That's what dying to self is all about.
I hope this makes sense. Take care & God bless!