God is a covenant-making promise keeper. The Bible reveals the character of God, and one thing it shows us over and over is God making agreements with his people and God doing what he says he will do. The covenants that God makes are similar to contracts between two parties, and in Genesis 9 he makes one of his very first ones. As the old spiritual says, “God gave Noah the rainbow sign, no more water but fire next time.” The rainbow is God’s signature, God’s John Hancock, written large in the sky for all to see. It’s a signature for the record books, and every time he writes it he is telling us, “see, I have kept my promise.”
The amazing thing about God’s agreement with Noah is that there is nothing that Noah has to do to keep this contract in force. God is making an unconditional guarantee. He says to Noah, “I establish my covenant with you: Never again will all life be destroyed by the waters of a flood; never again will there be a flood to destroy the earth.” There are no payments that Noah must make, no actions he or his descendants must take. It is all up to God. It is a kingly thing that God does, giving something that only he in his might and power could give and giving it forever.
God makes other covenants in the Bible, and some of them are conditional. He still makes them as the king, the one who holds the power to grant and the power to enforce, but in these agreements the other party has to hold up their end of the contract. God made such an agreement with Moses and the nation of Israel as he brought them out of their captivity in Egypt. He promised, as long as they kept his word and remained obedient to it, that he would bless them and make them a nation of kings and priests. He also promised them, if they failed to honor the covenant, that he would bring a curse upon them. The people willingly accepted the terms of the agreement, and then failed to keep their end of the bargain.
There is a final covenant that God has made with his people. He made it in graceful mercy when we failed to keep the old agreement. Here it is, from the words of the prophet Jeremiah as quoted by the writer of Hebrews:
“The days are coming, declares the Lord, when I will make a new covenant with the people of Israel and with the people of Judah. It will not be like the covenant I made with their ancestors when I took them by the hand to lead them out of Egypt, because they did not remain faithful to my covenant, and I turned away from them, declares the Lord. This is the covenant I will establish with the people of Israel after that time, declares the Lord. I will put my laws in their minds and write them on their hearts. I will be their God, and they will be my people. No longer will they teach their neighbor, or say to one another, ‘Know the Lord,’ because they will all know me, from the least of them to the greatest. For I will forgive their wickedness and will remember their sins no more.” Hebrews 8:8-12
You decide whether this is a conditional or unconditional covenant. But look at all that God says he will do: he will make a new covenant, he will put his laws in our hearts, he will forgive.
God is a covenant-making promise keeping God, and he likes to remind himself of it. That was the other reason for the rainbow. God put it there so that every time it appeared in the sky he would remember his promise.