This verse is notable partly because it contains the first use of the term “covenant” in Scripture, falling under the unwritten “Law of First Mention.” In the remainder of the Bible, it appears 252 more times. It is a significant term because of what “covenant” means to our relationship with God.
Theologians attach many definitions to it, such as the simple “a promise.” Charles Hodge defines it as “a promise suspended upon a condition, and [to which God] attached to disobedience a certain penalty.” Another termed it as “a bond sovereignly administered.” Modern legal terminology is adequate: “A covenant is a legal document establishing the terms of a relationship between parties involved together in the accomplishment of a purpose.”
Despite Genesis 6:18 being the first time “covenant” is used, it is not the first time the sense of a covenant appears in the Bible—and definitely not the last. It is but one of many to come as God's purpose unfolds. What does a covenant accomplish that assists both God's purpose and mankind's understanding of the life the Creator has given him? Humans need a clear understanding of this question if they are to have a good relationship with God. Deuteronomy 29:29 gives the answer: “The secret things belong to the LORD our God, but those things which are revealed belong to us and to our children forever, that we may do all the words of this law.”
Covenants, sometimes specifically and sometimes broadly, spell out each party's responsibilities within a relationship the parties have formed to accomplish a purpose. Biblically, a covenant may not be formally proposed and executed by God with man, as the sense of a covenant within a given context may be apparent to a thoughtful reader. Thus, what researchers call the Edenic Covenant is indeed a covenant even though it is not formally proposed, as the terms of the relationship between the Creator and those He created in Genesis 1 are easily discerned. Adam and Eve were to obey the Creator's rules as He personally revealed them and to do so without sin.
In like manner, some researchers perceive a second covenant, which they call the Adamic Covenant. Again, it is not formally proposed by God to Adam and Eve because their sins and the judgments God imposed so obviously altered life and the relationship between God and humanity. A formal declaration of a new covenant was not necessary. It appears after our first parents' sins and God's judgments, since those factors so seriously and obviously altered the relationships among all concerned.
Mark this truth well: The sins and their judgments altered not only the lives of Adam and Eve but also all who came after. Thus, their effects touch us too because those sins and God's judgments dramatically changed the world we live in (see Romans 8 for an expansion on this thought). Each covenant reveals God's purpose more explicitly to meet the demands of His purposes, but overall, as the “Big Picture” unfolds through the course of the Bible, it also reveals that His central purpose has never changed from the beginning. God declares in Malachi 3:6, “I am the LORD, I do not change; therefore you are not consumed, O sons of Jacob.”
The “Big Picture” reveals that God's purpose from the beginning has been to make man in His image and likeness. God did not cause us to sin; we have deliberately chosen to sin. We must live by faith and keep His commandments. We are saved by grace through faith, which is a gift of God. We must repent of sin and accept Jesus Christ, the Lamb slain from before the foundation of the earth, as our personal Savior. We must grow to love God with all our soul, mind, and might, and love our neighbor as ourselves.
The motivation for our submission to God has always been the wonderful mixture of trust in His Word—faith—combined with a deep, personal love for Him for what He is in His character. New elements are introduced with each covenant, as God's purpose is progressively developed to expand mankind's understanding. Each distinguishing mark of His purpose unfolds as humanity needs to understand its place in what is happening within God's creative process.
The Noahic Covenant, like the Edenic Covenant, is also a universal covenant. Though it is made with Noah, its purpose is to redefine the relationship between God and all mankind in the world that arises after the Flood. Only eight people remained. At least partly, this covenant was given so that Noah and ultimately all humanity could come to know that the Flood did not abolish the covenant following Adam's and Eve's sins and the application of God's judgments. Though the Flood was devastating, mankind is still bound to obey what was previously ordained. The Noahic covenant announces that the Flood did not change God's purpose. It did not wipe away man's original responsibilities, just the lawbreakers.