But here we must observe the words of the apostle; he calls him a servant that is occupied in works without faith, of which we have already treated at large; but he calls him a son which is righteous by faith alone.  The reason is this, altho the servant apply himself to good works, yet he does it not with the same mind as doth the son; that is, with a mind free, willing, and certain that the inheritance and all the good things of the Father are his; but does it as he that is hired in another man’s house, who hopes not that the inheritance shall come to him.  The works indeed of the son and the servant are alike; and almost the same in outward appearance; but their minds differ exceedingly:  as Christ saith, “The servant abideth not in the house forever, but the son abideth ever.”

Those of Cain’s progeny want the faith of sons, which they confess themselves; for they think it most absurd, and wicked arrogancy, to affirm themselves to be the sons of God, and holy; therefore as they believe, even so are they counted before God; they neither become holy nor the sons of God, nevertheless are they exercised with the works of the law; wherefore they are and remain servants forever.  They receive no reward except temporal things; such as quietness of life, abundance of goods, dignity, honor, etc., which we see to be common among the followers of popish religion.  But this is their reward, for they are servants, and not sons; wherefore in death they shall be separated from all good things, neither shall any portion of the eternal inheritance be theirs, who in this life would believe nothing thereof.  We perceive, therefore, that servants and sons are not unlike in works, but in mind and faith they have no resemblance.

The apostle endeavors here to prove that the law with all the works thereof makes us but mere servants, if we have not faith in Christ; for this alone make us sons of God.  It is the word of grace followed by the Holy Ghost, as is shown in many places, where we read of the Holy Ghost falling on Cornelius and his family while hearing the preaching of Peter.  Paul teaches that no man is justified before God by the works of the law; for sin only cometh by the law.  He that trusts in works condemns faith as the most pernicious arrogancy and error of all others.  Here thou seest plainly that such a man is not righteous, being destitute of that faith and belief which is necessary to make him acceptable before God and His Son; yea, he is an enemy to this faith, and therefore to righteousness also.  Thus it is easy to understand that which Paul saith, that no man is justified before God by the works of the law.