The worker must be justified before God before he can work any good thing.  Men judge the worker by the works; God judges the works by the worker.  The first precept requires us to acknowledge and worship one God, that is, to trust Him alone, which is the true faith whereby we become the sons of God.  Thou canst not be delivered from the evil of unbelief by thine own power, nor by the power of the law; wherefore all thy works which thou doest to satisfy the law can be nothing but works of the law; of far less importance than to be able to justify thee before God, who counteth them righteous only who truly believe in Him; for they that acknowledge Him the true God are His sons, and do truly fulfil the law.  If thou shouldst even kill thyself by working, thy heart can not obtain this faith thereby, for thy works are even a hindrance to it, and cause thee to persecute it.

He that studieth to fulfil the law without faith is afflicted for the devil’s sake; and continues a persecutor both of faith and the law, until he come to himself, and cease to trust in his own works; he then gives glory to God, who justifies the ungodly, and acknowledges himself to be nothing, and sighs for the grace of God, of which he knows that he has need.  Faith and grace now fill his empty mind, and satisfy his hunger; then follow works which are truly good; neither are they works of the law, but of the spirit, of faith and grace; they are called in the Scripture the works of God, which He worketh in us.

Whatsoever we do of our own power and strength, that which is not wrought in us by His grace, without doubt is a work of the law, and avails nothing toward justification; but is displeasing to God, because of the unbelief wherein it is done.  He that trusts in works does nothing freely and with a willing mind; he would do no good work at all if he were not compelled by the fear of hell, or allured by the hope of present good.  Whereby it is plainly seen that they strive only for gain, or are moved with fear, showing that they rather hate the law from their hearts, and had rather there were no law at all.  An evil heart can do nothing that is good.  This evil propensity of the heart, and unwillingness to do good, the law betrays when it teaches that God does not esteem the works of the hand, but those of the heart.

Thus sin is known by the law, as Paul teaches; for we learn thereby that our affections are not placed on that which is good.  This ought to teach us not to trust in ourselves, but to long after the grace of God, whereby the evil of the heart may be taken away, and we become ready to do good works, and love the law voluntarily; not for fear of any punishment, but for the love of righteousness.  By this means one is made of a servant, a son; of a slave an heir.