I always thought "Nobody's Perfect" was just a convenient excuse for messing up.

Growing up, the goal was to try and be good...after all, "nobody's perfect," right?

Imagine my surprise when I heard, "Be ye therefore perfect, even as your Father which is in heaven is perfect." (Matthew 5:48)  It's hard enough trying to be good, but perfect?

Then I hear, "There is none good, no not one." (Romans 3:12)

I'm not a Greek Scholar, but even a cursory study of scripture shows that the word Paul uses for "good" in Romans, is "chrestotes." "Chrestotes" means "usefulness." 

This wasn't a blanket declaration that people can't be "good," Paul was simply referring to a group of people who had become "useless."

Nevertheless, Jesus didn't say be "good," he said be "perfect" (teleios)...it means "complete."  To be "complete," we need the indwelling of the Spirit.  As he said, "Ye must be born again."  When you're born again, you will do good and you will obey...not because you have to, but because you want to.  Your highest priority will be to please God.  If that's not your highest priority, you haven't been reborn Spiritually.

Until you're reborn Spiritually...nothing else matters.