These two parts of God's Word join seamlessly to provide God's complete revelation to mankind. Even though the period between the testaments was more than 400 years, the writings of the Hebrew prophets precede the apostolic writings in a manner that emphasizes their basic unity.
Consider how the closing words of the Old Testament prophets flow smoothly into those that open the New Testament. Malachi, generally considered to be the last of the Hebrew prophets, foretells an "Elijah who is to come"—John the Baptist (Matthew 11:13-14 Matthew 11:13-14  For all the prophets and the law prophesied until John.
 And if you will receive it, this is Elias, which was for to come.
American King James Version×; Malachi 4:5-6 Malachi 4:5-6  Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the LORD:  And he shall turn the heart of the fathers to the children, and the heart of the children to their fathers, lest I come and smite the earth with a curse.
American King James Version×).
Mark, considered by many to have been the first of the Gospel writers, begins right where Malachi left off—citing prophecies from Malachi 3:1 Malachi 3:1Behold, I will send my messenger, and he shall prepare the way before me: and the LORD, whom you seek, shall suddenly come to his temple, even the messenger of the covenant, whom you delight in: behold, he shall come, said the LORD of hosts.
American King James Version×and Isaiah 40:3 Isaiah 40:3The voice of him that cries in the wilderness, Prepare you the way of the LORD, make straight in the desert a highway for our God.
American King James Version×of a messenger who would precede the Messiah. Then John the Baptist (the Elijah to come prophesied by Malachi) is introduced as the appointed forerunner of Jesus Christ, establishing the way for His first coming. (It is interesting to note that the context of the final chapter of Malachi also implies the appearance of still another prophet "in the spirit and power of Elijah" who will precede Christ's second coming.)
Matthew similarly begins his Gospel as a continuation of the Old Testament, giving a genealogy of the Hebrew patriarchal and kingly lines leading to the birth of Jesus Christ. The specific purpose in Matthew 1 is summed up in Matthew 1:18 Matthew 1:18Now the birth of Jesus Christ was on this wise: When as his mother Mary was espoused to Joseph, before they came together, she was found with child of the Holy Ghost.
American King James Version×: "Now the birth of Jesus Christ was as follows . . ."
Yet 17 vital verses precede this statement. Why? These boldly declare Jesus Christ's Israelite ancestry back to King David and, even earlier, to Abraham. These words of Matthew validate the importance of the earlier books of the Hebrew Bible and demonstrate how he was building on their foundation.
Why does the New Testament begin with a genealogy?
"The book of the genealogy of Jesus Christ, the Son of David, the Son of Abraham: Abraham begot Isaac, Isaac begot Jacob, and Jacob begot Judah and his brothers . . . David the king begot Solomon by her who had been the wife of Uriah . . . Josiah begot Jeconiah and his brothers about the time they [the peoples of Judah] were carried away to Babylon . . .
"So all the generations from Abraham to David are fourteen generations, from David until the captivity in Babylon are fourteen generations, and from the captivity in Babylon until the Christ are fourteen generations" (Matthew 1:1-17 Matthew 1:1-17  The book of the generation of Jesus Christ, the son of David, the son of Abraham.
 Abraham begat Isaac; and Isaac begat Jacob; and Jacob begat Judas and his brothers;
 And Judas begat Phares and Zara of Thamar; and Phares begat Esrom; and Esrom begat Aram;
 And Aram begat Aminadab; and Aminadab begat Naasson; and Naasson begat Salmon;
 And Salmon begat Booz of Rachab; and Booz begat Obed of Ruth; and Obed begat Jesse;
 And Jesse begat David the king; and David the king begat Solomon of her that had been the wife of Urias;
 And Solomon begat Roboam; and Roboam begat Abia; and Abia begat Asa;
 And Asa begat Josaphat; and Josaphat begat Joram; and Joram begat Ozias;
 And Ozias begat Joatham; and Joatham begat Achaz; and Achaz begat Ezekias;
 And Ezekias begat Manasses; and Manasses begat Amon; and Amon begat Josias;
 And Josias begat Jechonias and his brothers, about the time they were carried away to Babylon:
 And after they were brought to Babylon, Jechonias begat Salathiel; and Salathiel begat Zorobabel;
 And Zorobabel begat Abiud; and Abiud begat Eliakim; and Eliakim begat Azor;
 And Azor begat Sadoc; and Sadoc begat Achim; and Achim begat Eliud;
 And Eliud begat Eleazar; and Eleazar begat Matthan; and Matthan begat Jacob;
 And Jacob begat Joseph the husband of Mary, of whom was born Jesus, who is called Christ.
 So all the generations from Abraham to David are fourteen generations; and from David until the carrying away into Babylon are fourteen generations; and from the carrying away into Babylon to Christ are fourteen generations.
American King James Version×).
These 17 verses may be viewed as a brief summary of the sacred history of Israel and Judah. They send a powerful message at the beginning of the New Testament that we must give the Old Testament due consideration.
Matthew's historical introduction is designed to show Christ's legal genealogy—that He is the fulfillment of promises made to Abraham (Genesis 12:3 Genesis 12:3And I will bless them that bless you, and curse him that curses you: and in you shall all families of the earth be blessed.
American King James Version×; Genesis 18:18 Genesis 18:18Seeing that Abraham shall surely become a great and mighty nation, and all the nations of the earth shall be blessed in him?
American King James Version×; Genesis 22:18 Genesis 22:18And in your seed shall all the nations of the earth be blessed; because you have obeyed my voice.
American King James Version×; etc.) and to King David (compare 2 Samuel 7:16 2 Samuel 7:16And your house and your kingdom shall be established for ever before you: your throne shall be established for ever.
American King James Version×; Acts 13:22-23 Acts 13:22-23  And when he had removed him, he raised up to them David to be their king; to whom also he gave their testimony, and said, I have found David the son of Jesse, a man after my own heart, which shall fulfill all my will.  Of this man's seed has God according to his promise raised to Israel a Savior, Jesus:
American King James Version×; Luke 1:32 Luke 1:32He shall be great, and shall be called the Son of the Highest: and the Lord God shall give to him the throne of his father David:
American King James Version×). Matthew's Gospel is built upon the foundation of the Hebrew Scriptures and contains many quotations from them. Thus both Matthew and Mark link the two testaments as a complete and whole revelation.