By nature human beings are made in such a way that they do not want to accept anything from God free of charge but want to earn it by their works and their righteousness. It is diabolical arrogance not to want to get anything from God free of charge but to earn everything, because this is saying that we want to be God ourselves. This is what Adam began in the garden and from there it has spread to the entire human race.
Admittedly there is a danger in teaching justification by faith to people who are rebellious and despisers of religion. But just because there is a danger in doing this, it does not follow that the church should be deprived of what is necessary for its salvation. There is danger in producing wine, because people get drunk on wine. Yet God has created wine, which is healthy if used in the right way... No work of the moral or ceremonial law can justify us in the sight of God because no work can be done by us with the degree of perfection and integrity that would be needed for God to accept it. All our good works are imperfect and corrupt. Therefore they cannot justify us... When it is said that the Gentiles are not justified by the works of the law, this does not mean that good works that are moral or part of the natural law are not to be encouraged. Of course the natural law must be observed, and anyone who does not follow it is ungodly and worse than an infidel. What it means is that the merits of our good works have no validity in the judgment of God, nor do they delivery us from the sentence of condemnation. So we must do the works of the natural law but not think that they can save us from perishing or acquit us before the judgment seat of God. There is another kind of righteousness, namely the righteousness of Christ, which is perfect and which is received by faith.
Johannes Brenz, from The Reformation Commentary on Scripture, Galatians, Pg. 70-71