What would a solid Reformed Dutch pastor from around 1700 mention in a sermon with these themes? The covenant of works, among other things. Here are a few quotes from Johannes Vanderkemp (d. 1718), translated from the Dutch in 1810.
“This law hath a respect also to the covenant of works, as the condition of it, which God demanded of man, with a promise of life, and a threatening of death….”
Concerning Gen 2.17, Vanderkemp preaches, it “can be considered only as a probationary command whereby Adam was to be proved for some time, whether he would continue good, or become evil, and whether he would love God more than the creature, or the creature more than God; as the Savior commanded that presumptuous young man to ‘sell all his goods, and give to the poor,’ that he might prove him, whether he had, as he pretended, truly ‘kept the whole law from his youth up’ Matt 19.17, 22.”
“This demand God enforced with the promise of life, that he might encourage Adam to observe it perfectly: ‘For Moses describeth the righteousness which is of the law, that the man who does those things shall live by them,’ as Paul explains it, Rom. 5.5, which life was sealed to him by the tree of life. By this life we must understand not only corporal and spiritual, but eternal life: and that not only in Paradise, but also in heaven itself, into which he should be admitted after the time of his probation. For whatever the elect sinner obtains by Christ; he lost by Adam, and therefore also everlasting life in heaven.”
Later on, he says, “All the parts of the covenant of works are opposed to all the parts of the covenant of grace, as ‘Adam and Christ’ Rom 5, 1 Cor 15, ‘Works and grace,’ Rom 6.14, 11.6 ‘The law of works and the law of faith,’ Rom 3.27, 28, see also Rom 7.3,4.”
“This is the sense in which the catechism uses the word nature here (Q/A 5); for it speaks of a man who lives yet under the broken covenant of works, who is a ‘child of wrath by nature,’ Eph 2.3….”
Johannes Vanderkemp, The Christian Entirely the Property of Christ, in Life and Death, Exhibited in Fifty-three Sermons on the Heidelberg Catechism trans. John M. Harlingen, (Grand Rapids: Reformation Heritage Books, 1997), 22-27.