The prophet Isaiah knew that the true and living God is a covenant-making and covenant-keeping God. He writes of a “covenant of peace”(Isa. 54:10) and of an “everlasting covenant” (Isa. 55:3) between God and His people. This Covenant is clearly meant to be a blessing and encouragement to the people of God. But what is a covenant?

One brief definition of covenant is “a structured relationship.” God establishes and structures the fellowship that He has with us. Thus, the covenant is like a treaty that specifies the benefits and duties that bind the two parties together.

Most Reformed theologians understand the Bible as teaching that the first covenant God initiated was with Adam in the Garden of Eden. Although the word covenant is not used in reference to Adam in Genesis, God clearly structured His relationship with Adam in terms of duties and benefits. Hosea6:7speaks of Adam in relation to covenant: “But like Adam they have transgressed the covenant …” (NASB). The Westminster Confession summarizes that teaching about God's relationship with Adam: “The first covenant made with man was a covenant of works, where in life was promised to Adam, and In him to his posterity, upon condition of perfect and personal obedience” (VII.2). In the first covenant, life was promised to those who fulfilled the duty of obedience.

Adam, and with him all of mankind, fell into sin and disobedience, and therefore deserved the sentence of death. But God in mercy established a different covenant for sinners, which usually is called the covenant of grace. The Westminster Confession summarizes this gracious covenant as one” whereby He freely offereth unto sinners life and salvation by Jesus Christ; requiring of them faith in Him, that they may be saved; and promising to give unto all those that are ordained unto eternal life His Holy Spirit, to make them willing, and able to believe” (VII.3). The covenant of grace is presented as the blessing of life and salvation linked to the duty of faith, but since faith is a gift of God, even the requirement of faith is a blessing given!

This covenant of grace was announced to Adam and Eve in the garden (Gen.3:15), and is at the root of all other covenantal agreements in the Bible, including God's covenants with Abraham, Moses, and David They all come to fruition in the coming of Jesus and the great redemptive work that He did to save sinners.

Fulfillment of the previous covenants is actually the kernel of the Gospel. Jesus is our Second Adam, the head of a new covenant community and a new humanity. He fulfills the condition of perfect, personal obedience. By His death, He bears the wrath of God, so that in Him sinners might be forgiven and enlivened. All that Jesus did, He did to establish the covenant of grace between God and mankind. He fulfilled all the conditions of the covenant, either for us or in us.

Because of the great work of Jesus—either as promised in the Old Testament or as fulfilled in the New Testament-the word covenant is a special treasure for the people of God. With God's great plan in mind, we can turn to Isaiah's references to the covenant with a renewed understanding and appreciation.

God declared, ‘“For the mountains shall depart and the hills be removed, but My kindness shall not depart from you, nor shall My covenant of peace be removed,' says the LORD, who has mercy on you” (Isa. 54:10). Here the Lord assures His people of His unfailing care, which is more certain even than the mountains and the hills. The earth itself will disappear before the mercy of the Lord will depart from His own regenerate people.

That mercy is also called His “kindness.” In some translations, that Hebrew word (hesed) is rendered “lovingkindness” or “unfailing love.” It is God's special, unique saving love for His own. It might well be translated “covenant love.” The unfailing covenant love of the Lord assures us that we have peace with God. Nothing that we could do would bring us that reconciliation with God. But Jesus as the Lord of the covenant ministers that forgiveness and peace to us. As believers who know that we are right with God, we can respond with the wonderful words of Isaiah (found in chapter 54) recognizing God to be our Maker, redeemer, husband, LORD of hosts, Holy One, and God of the whole earth.

We also find a reference to the covenant of grace in Isaiah 55:3: “Incline your ear, and come to Me. Hear, and your soul shall live; and I will make an everlasting covenant with you – the sure mercies of David.''' Here the promise is that God's covenant is everlasting and unchanging, though conditional upon their faithful response to it.

Sinners have an everlasting covenant because of the work of Christ. Again the Westminster Confession expresses this well:”The Lord Jesus, by His perfect obedience and sacrifice of Himself, which He through the eternal Spirit once offered up unto God, hath fully satisfied the justice of His Father; and purchased not only reconciliation, but an everlasting inheritance in the kingdom of heaven, for all those whom the Father hath given unto Him” (VIII. 5). Because we have an everlasting and unchangeable covenant, we have an everlasting inheritance. How rich is the covenant mercy of God to us!