What are Good Works?

Good Works are those that God commands us in his word to do. Nothing more and nothing less. Jeremiah 7:21-23, Deuteronomy 12:8, 32, and Jeremiah 32:35


John Calvin also says, "Now, since the Lord, when about to deliver a rule of perfect righteousness, referred all the parts of it to his own will, this shows that nothing is more acceptable to him than obedience. This is worthy of the most diligent observation, since the licentiousness of the human mind is so inclined to the frequent invention of various services in order to merit his favour. For this irreligious affectation of religion, which is a principle innate in the human mind, has betrayed itself in all ages, and betrays itself even in the present day, for men always take a pleasure in contriving some way of attaining righteousness, which is not agreeable to the Divine word. Hence among those which are commonly esteemed good works, the precepts of the law hold a very contracted station, the numberless multitude of human inventions occupying almost the whole space. But what was the design of Moses, unless it was to repress such an unwarrantable license, when, after the promulgation of the law, he addressed the people in the following manner! 'Observe and hear all these words which I command thee, that it may go well with thee, and with thy children after thee for ever, when thou doest that which is good and right in the sight of the Lord thy God. What thing soever I command you, observe to do it thou shalt not add thereto, nor diminish from it.'" - The Institutes, 2. 8. 5.

Calvin also says, "We are certainly bound by the same declaration, for the claims of the Lord on behalf of his law, that it contains the doctrine of perfect righteousness, beyond all doubt remain perpetually the same; yet not contented with it, we are wonderfully laborious in inventing and performing other good works, one after another. The best remedy for this fault will be a constant attention to this reflection, that the law was given to us from heaven to teach us a perfect righteousness, that in it no righteousness is taught, but that which is conformable to the decrees of the Divine will; that it is therefore vain to attempt new species of works in order to merit the favour of God, whose legitimate worship consists solely in obedience, but that any pursuit of good works deviating from the law of God is an intolerable profanation of the Divine and real righteousness." - The Institutes, 2. 8. 5.

Here we have it from Calvin that good works are  what God commands as oppose to what many so-called 'Christians' who have never read their Bibles think of good works as something done for the nilly willy of it.

Martin Luther and Assurance

"But you say, how can I be absolutely sure that all my works are pleasing to God, when at times I fall, talk,eat, drink and sleep too much, or otherwise transgress in ways I cannot avoid? Answer: This questions shows that you still regard faith as a work among other works and do not set it above all works. It is the highest work because it blots out these everyday sins and still stands fast by never doubting that God is so favorably disposed toward you that he overlooks such everyday failures and offenses. Yes, even if a deadly sin should arise (which, however, never or rarely happens to those who live in faith and trust in God), nonetheless faith always rises again and does not doubt that its sin is already gone. As it is written in 1 John 2 [:1-2], 'My dear children, I am writing this to you so that you may not sin; but if any one does sin, we have an advocate before God, Jesus Christ, who is the forgiveness for our sins.'" - Martin Luther, Treatise on Good Works

Gottschalk on Double Predestination and Equally Ultimacy

"I believe and confess that the omnipotent and immutable God has gratuitously foreknown and predestined the holy angels and elect human beings to eternal life, and that he equally predestined the devil himself, the head of all the demons, with all of his apostate angels and also with all reprobate human beings, namely, his members, to rightly eternal death, on account of their own future, most certainly foreknown evil merits, through his most righteous judgment." - Gottschalk of Orbais

Gottschalk on Limited atonement and Double Predestination

"All those impious persons and sinners for whom the Son of God came to redeem by shedding his own blood, those the omnipotent goodness of God predestined to life and irrevocably willed only those to be saved. And again all those impious persons and sinners for whom likewise the Son of God neither assumed a body nor prayed, I say that he did not shed [his] blood nor was in any way crucified for them. In fact, those whom he foreknew were going to be very evil and whom he very justly foreordained unto eternal torments into which they should be cast, he thoroughly does not want them in any way to be eternally saved.
Therefore, I very faithfully believe, very confidently speak, and likewise most certainly and fruitfully confess and most truthfully profess that our omnipotent God, the creator and maker of all creatures, has deigned to be the gratuitous repairer and restorer of all of the elect alone, but willed to be the Savior of none of the perpetually reprobate, the redeemer of none, and glorifier of none." - Gottschalk of Orbais