Here, this command is directly given to Adam before the creation of Eve. Whether Eve knew of this command directly from God or not, I am unsure. But I have no doubt that she knew that she should not eat of the tree. Adam had one requirement: if he obeyed he would earn eternal life for himself and his posterity, if not he and his descendants after him will be born sinful and be condemned–they will die (see chapter 7 on the Covenant Of Works). Adam, in the Garden of Eden, stood in the stead of all people that would come from him. See paragraph 3 for federal headship. Most importantly, the Fall is recognized to not be outside of God’s sovereign decree, but in it. It pleased God to “permit” it, why? Because He had “purposed to order it to his own glory.” In what way? By displaying a wider range of His attributes: by putting His wrath on display and by putting His grace on display; by conquering evil and getting glory over it; by saving His elect from the world; by becoming man in the process of saving the world. All these glorious things could not have happened if God had not decreed the Fall.
The first sin may be the most difficult question to answer as to how it could have been that a perfectly good being like Adam or Satan could rebel and fall. What would cause them to do that? Free will has no explanatory power. We do not believe that it sufficiently answers the question. That’s why the Fall and every sin needs to be recognized as ordained by God of old and is purposed to display His glory. Sin is never outside of God’s control. It is indeed mysterious why would or how would a “very good” (Gen. 1:31) creature rebel against God. I reject the notion that there is no freedom without the opposite, that is, man must have the ability to obey and disobey to be truly free (see chapter 9 on free will). The Persons of the Blessed Trinity have always obeyed each other and never done anything contrary, yet God is most free and sovereign. The Lord Jesus has only done what the Father pleases, but that does not mean that He is not free because He cannot but love and obey His Father.
When God created, He consciously created Adam as a type of Christ. Adam did not become a type after the Fall, or when Paul wrote Romans, but he was, in fact, created as a type, he did not become one.
Rom. 5:14 Yet death reigned from Adam to Moses, even over those whose sinning was not like the transgression of Adam, who was a type of the one who was to come.
This would mean that Adam was created to point to Christ and display Christ. But this also means that Christ came to do that which Adam was supposed to do. When we look at what Christ accomplished, we can also look back to Adam and see what he was supposed to accomplish had he obeyed God in his time of probation. We can learn about the type from the antitype and vice-versa.
The fact that God predestines us to be holy and blameless presupposes that we would not be holy and blameless, and that God had purposed to permit the Fall. Therefore, God, before the creation of the world, predestined people to be sinless:
Eph. 1:3-6 Blessed be the God and Father of our Lord Jesus Christ, who has blessed us in Christ with every spiritual blessing in the heavenly places, 4 even as he chose us in him before the foundation of the world, that we should be holy and blameless before him. In love 5 he predes...