Looking back: There is a Chain of Command that connects the Old and New Testaments of the Bible into one testimony: the testimony of Christ.
The promise: A coming Prophet, Priest and King
In the Old Testament is recorded the history of Man on Earth, and that of Israel as a nation. God did this so future generations could read it and judge whether it was true or not. God wants us to know who he is, and to this end he left a record not only of the past, but of the future.
God, after he delivered Israel from slavery in Egypt, gave them a law to live by and a hope for the future. He made a promise to them, recorded in Deuteronomy 18, that another prophet, like Moses, would be raised up from among their own brethren. The text reads as follows:
17 The LORD said to me: "What they say is good.
18 I will raise up for them a prophet like you from among their brothers; I
will put my words in his mouth, and he will tell them everything I command him.
19 If anyone does not listen to my words that the prophet speaks in my
name, I myself will call him to account. (Deuteronomy 18:17-19, circa 1400 B.C.)
This passage, written down in the 14th centery B.C., tells us there would come another prophet, that he would be a Jew, and that his words would be the very words of God. So begins the Chain of Command.
Eight hundred years later, God promised Israel, through Jeremiah his prophet, a New Covenant. The text is found in Jeremiah 31:31-36, a passage quoted later in Hebrews 8 of the New Testament. This passage also asserts that Israel will never cease to be a nation before God.
God planned to install another priesthood, one after the order of Melchizedek, and NOT after the manner of the Levitical one set forth in the Law. That priesthood would last forever. The King of God's choosing is mentioned in the same place. The text is found in Psalms 110 (circa 1000 B.C.) (Another reference to God's King is found in Psalms 2).
So Israel was to expect a future Prophet, future Priest and future King.
The New Testament would later quote the above passages in connection with
the testimonies of Jesus Christ. Sermons preached in the book of
Acts contain these quotes:
Acts 2:32-36 quotes Psalms 110 in connection with Christ
Acts 3:22-25 quotes Deuteronomy 18 in connection with Christ
The longest Old Testament quote found in the New Testament is in Hebrews chapter 8, where Jeremiah 31: is quoted to show Chist as high priest of that New Covenant.
Enter, the promises of Christ
One important promise Jesus left us is that the Holy Spirit would indwell the Church, and that the teachings of his apostles would be the very words of God. What the disciples could not know then, they would know later:
In John 13:7 Jesus, unfolding the future ministry of the Holy Spirit,
7 But I tell you the truth: It is for your good that I am going away. Unless I go away, the Counselor will not come to you; but if I go, I will send him to you.
And again, in verses 12-13:
12 "I have much more to say to you, more
than you can now bear.
13 But when he, the Spirit of truth, comes, he will guide you into all truth. He will not speak on his own; he will speak only what he hears, and he will tell you what is yet to come.
And again, in John 14:25-26:
25 "All this I have spoken while still with
26 But the Counselor, the Holy Spirit, whom the Father will send in my name, will teach you all things and will remind you of everything I have said to you. (John 14:25-26)
20 Remember the words I spoke to you: `No servant is greater than his master.' If they persecuted me, they will persecute you also. If they obeyed my teaching, they will obey yours also. (John 15:20)
26 "When the Counselor comes, whom I will send to you from the Father, the Spirit of truth who goes out from the Father, he will testify about me.
27 And you also must testify, for you have been with me from the beginning. (John 14:26-27)
So in these passages, God puts his imprimatur on the future writings of all who were present in the upper room with him.
So where was Paul?
Paul, who would later write 14 epistles to the Church, was NOT present to hear Jesus' words. He wasn't even a disciple at the time Jesus made these promises. So how can we know that his writings are from God?
We can know, because Peter WAS there,. and through him the chain of command extends to Paul, as is written in Peter's second letter, saying:
15 Bear in mind that our Lord's
patience means salvation, just as our dear brother
Paul also wrote you with the wisdom that God gave him.
16 He writes the same way in all his letters, speaking in them of these matters. His letters contain some things that are hard to understand, which ignorant and unstable people distort, as they do the other Scriptures, to their own destruction. (2 Peter 3:15-16)
So Peter, present with the Lord in the upper room and heir of God's promises, speaking by the Holy Spirit, tells us that the writings of Paul are equal to those of the Old Testament, including the writings of the other apostles.
So the Word of God, from Moses to the Apostles, forms an unbroken chain of command we may refer to as "The testimony of Christ."