‘Sin’ vs. ‘Sins’ , and the ‘spiritual muscle building’ game

Many folks in the Church really like to keep busy by pumping their ‘spiritual muscles’. They’ve substituted the Charles Atlas (I’m dating myself) poster on the wall, for a poster of Jesus and the Sermon on the Mount. 80's Muscle Mom # 2

I believe that Jesus’ sermon was a re-presenting of God’s perfect Law, wherein no one would be left with any wiggle room at all when it came to living their lives in the manner that God demands. 

However, many well meaning preachers and teachers in the Church today believe that it is proper  to convince Christians that they can become better Christians by addressing their sins. ( a short audio clip of less than 10 minutes).

Is it possible to become a better Christian by addressing your sins?

Thanks for your input!