"When you feel yourself declared righteous on the basis of the righteousness of Christ because it has imputed to you by union with Christ you are liberated for huge undertakings for God. You can risk anything for God. It produces a Reformation. The western world. It produces the protestant work ethic..." John Piper in the Theology Network Podcast, Table Talk #4.
It makes all the difference to life whether I'm living to impress people or knowing I'm accepted by God because of Jesus. In the first case I have to show off, cover failings and go into denial. In the latter it's not that I boast in my sin, but I can be honest about it and proceed to repentance.
I'm struck that in Genesis 4 Cain is a sin-denier as he attempts to cover up his crime of murder. His descendent Lamech is also a killer, but he boasts in his sin. Where God graciously protected Cain - for Vengeance is the Lord's not for man to claim, Lamech presumed to proclaim his own vengeance. One legalistic generation can easily give way to a licentious one. Such are the ways of The Serpent.
But those who are justified need not swing to one extreme or the other. The justified live in The Seed of the Woman, the defeater of the Serpent who gifts right-standing, new-life, new-status, new-present and new-future to his people. Those "justified by faith" look deeply different to those who make their own way. They are truly liberated people.
Their lives will look different in all areas. It effects work. The sinful mind imagines that if someone is already fully accepted then they will become lazy. But, this is far from the truth. Justification by faith produced "the protestant work ethic" - liberated from a performance ethic, knowing that work matter and can be done to the glory of God the justified person is free to work hard and motivated to do so. Not because I have to, but because I get to. Not because I get my identity from what I achieve, but because it comes from the work that he has done. Justification overflows into work.