The counter-argument for someone propounding the Covenant of Works is that just because the word Covenant is not found in the garden does not necessarily mean there was no covenant. I agree. However, the conspicuous absence of both the word and it's concept is another matter entirely.There are over 300 instances of Covenant it in the Bible, but none in the garden account. While God could have dropped that word anywhere, He waits until after the fall to trot it out. Let's look at the big covenant instances now to show you what I mean.
The Covenant with Noah
Here is the first time, (Gen 9:9, 11) "And as for Me, behold, I establish My covenant with you and with your seed after you... Thus I establish My covenant with you: Never again shall all flesh be cut off by the waters of the flood; never again shall there be a flood to destroy the earth." I'll mention how to understand this in a second, for now lets continue on.
The Covenant with Abraham
The next time comes at Genesis 15:18 with Abraham "On the same day the LORD made a covenant with Abram, saying: "To your seed I have given this land, from the river of Egypt to the great river, the River Euphrates" Abraham then becomes disobedient and causes God to wait, but once he is faithful again God speaks the rest, "And I will establish My covenant between Me and you and your seed after you in their generations, for an everlasting covenant, to be God to you and your seed after you." (Genesis 17:7), which of course is talking about Christ (Galatians 3:16) "Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ."
That passage in Galatians changes everything, because it bonds Covenant to Christ. And if God did indeed want to do that, to make those two items connected in our mind, then He must wait until after the fall to introduce the idea of a Redeemer and Savior. Which fits, which is why He waits until post fall to use the word Covenant. Is this not what Isaiah prophesied about when talking about Christ? "I will keep You and give You as a covenant to the people" (Isaiah 42:6)
That would mean we are not to understand the Noah passage by drawing it backwards to Adam, but forward to Christ. God was telling Noah that he would send someone to prevent the earth from being destroyed. He would restrain future wickedness and keep it from getting to that point again. He would send someone in righteousness to preserve a people for Himself.
The Covenant at Sinai
The next instance of Covenant comes from Sinai, mediated by God's servant Moses. (Exodus 34:27; Deut 4:13) Here God gives His people a priesthood for the cleansing of sins (the blood of the Covenant), an ark of the Covenant to encase the promise in, and Tablets to remind them (Exodus 24:7-8; Deut 9:9). As a sign God gives them the Sabbath rest (Ex 31:13). The thrust of this one is obedience to God, principally seen in keeping the rules.
It's to this covenant that the writers of the NT appeal, Galatians and Hebrews in particular, and their point is it's all about Christ. Christ the Son is contrasted with Moses the servant, (Heb 3:2-6). Christ is the Sabbath rest (Heb 3:10-4:13), the new and better high priest offering sacrifice on behalf of the people, (4:14-5:7, 7) who was obedient to God (Heb 5:8-9). He Himself was the new and better ark of the covenant, the new and better tabernacle, the new and better offering. Everything that Sinai was pointing toward, He was. His shed blood was that new Covenant pointed to in Jeremiah, (1 Cor 11:25) as He said (Luke 22:20).
Even the rules themselves, while promising eternal life, were really the signposts pointing them on to Christ. The Jews did not understand this aspect of Sinai, they didn't see Him in it because they were blind (2 cor 3:15, Rom 11:7), they sought to establish their own righteousness (Romans 10:3-4), instead of seeing that the Covenant rules at Sinai really were given to show them Christ. For what does Paul say? (Gal 3:19, 22-24) "What purpose then [does] the law [serve]? It was added because of transgressions, till the Seed should come to whom the promise was made; [and it was] appointed through angels by the hand of a mediator... But the Scripture has confined all under sin, that the promise by faith in Jesus Christ might be given to those who believe. But before faith came, we were kept under guard by the law, kept for the faith which would afterward be revealed. Therefore the law was our tutor [to bring us] to Christ, that we might be justified by faith."
In sum, the Covenant at Sinai it builds on the other promises/Covenants already given to the saints. It does not supplant the promises, it increases it. Each successive covenant teach us more and more about Christ.
The Covenant to David(2 Samuel 7:14, Jeremiah 33:21) "I will be his father, and he shall be my son. If he commit iniquity, I will chasten him with the rod of men, and with the stripes of the children of me"
This is pointing us on to Christ again, even though we make a stop over at Solomon as a partial fulfillment. I don't think much needs to be said here since it's so obvious, so let's go on.
The New Covenant
The new covenant is Christ. Jeremiah 31:31-33, 38) "Behold, the days are coming, says the LORD, when I will make a new covenant with the house of Israel and with the house of Judah-- "not according to the covenant that I made with their fathers in the day [that] I took them by the hand to lead them out of the land of Egypt, My covenant which they broke, though I was a husband to them, says the LORD. "But this [is] the covenant that I will make with the house of Israel after those days, says the LORD: I will put My law in their minds, and write it on their hearts; and I will be their God, and they shall be My people. 'And I will make an everlasting covenant with them, that I will not turn away from doing them good; but I will put My fear in their hearts so that they will not depart from Me." And as Hebrews teaches us this is the promise of eternal life, that if we believe in Christ He will save us. He is going to once and for all mend all the damage done in Eden, He will save His people, adopt them, regenerate them, and be with them forever. This promise is fulfilled by, in, and through Christ Jesus.
Adam couldn't have received a covenant before the fall because there was no place, no need, no room for Christ to come. Covenant means Christ. If Adam receives a covenant then it's the promise given in Genesis 3:15 "And I will put enmity between thee and the woman, and between thy seed and her Seed; He shall bruise thy head, and thou shalt bruise His heel."
It cannot be in the charge Adam was given to watch over Eden, because it wasn't in Eden.