As recorded in the Bible, how did Jesus (New Testament) fulfill the Old Covenant (The Old Testament)?
God made promises, or covenants, with the Chosen People, who came to be known as the Israelites, at several times through the history recorded in the Old Testament. Many of those covenants included prophetic statements about the future that were fulfilled through Jesus's life, death, and resurrection.
When God first chose Abram to be the father of God's special people, God promised, "I will make you into a great nation and I will bless you...and all peoples on earth will be blessed through you." (Gen. 12:2-3) From this first promise, God pledged that all people would come to know the blessings of God, not just Abram's descendents. When Jesus commissioned His disciples to "go and make disciples of all nations" (Matt. 28:19), He was setting into motion the fulfillment of God's promise.
When King David had solidified his position on the throne, he determined to build a Temple for the worship of God. Through the prophet Nathan, God told David that it was not his role to build a Temple. However, God extended a great promise to David:
When your days are over and you rest with your fathers, I will raise up your offspring to succeed you, who will come from your own body, and I will establish his kingdom...Your house and your kingdom will endure forever before me; your throne will be established forever. (2 Sam. 7:12, 16)
Jesus, a lineal descendent of David, became the realization of this promise.