"But sanctify the Lord God in your hearts: and be ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear:" 1 Peter 3:15 (KJV)
God is a God of covenants not a God of contracts. Contracts are sealed with a signature and there are legal ways to break them. A covenant is established by God, sealed with blood and unbreakable.
The Covenant with Noah (Genesis 8:20-9:17) This is a Covenant of hope. In the rainbow we see the sign that God has not given up on us. As long as we are able to see that rainbow there is hope. With eight people God gave us a new beginning.
The Covenant with Abraham (Genesis 17:1-21) This is the start of a new nation; a nation chosen by God to reveal Himself to the world. With Abraham we saw a peculiar people, the carriers of God’s blessings to the world.
The Covenant with Moses (Exodus:3-6) Through Moses God gave us the law, the heart of God in written words, the only acceptable way of the Lord and His holy standards. With Moses we saw the will of God for His people, His precious holiness and His righteous ways.
The Covenant with David (2 Samuel 7:8-17) This is the promise that God’s Kingdom is to be established forever. Out of the seed of David came the King of kings and the Lord of lords in the flesh… our Lord and Savior Jesus Christ.
The New Covenant (Jeremiah 31:1-37 / Isaiah 40:1-11) Here God gave us a better covenant and the promise that God will indeed write the laws that He gave to Moses in the hearts of those that embrace His son. The New Covenant is filled with grace and with truth through Jesus Christ. The New Covenant is indeed the last covenant sealed not with the blood of animals, but with the blood of our Eternal King. Jesus shed His blood, died a horrible death on the cross in Calvary, but on the third day he roused again.