Q: How does Christ execute the office of a prophet?
A: Christ executes the office of a prophet, in revealing to us, by his word and Spirit, the will of God for our salvation.
Acts 1:8 But you will receive power when the Holy Spirit has come upon you, and you will be my witnesses in Jerusalem and in all Judea and Samaria, and to the end of the earth.
A prophet, in the Biblical sense, was someone who brought the Word of God to the people. Jesus Christ, of course, is the ultimate revelation of God's Word. We might think of John's words at the beginning of his gospel when he writes of Jesus, "the Word became flesh". Christianity teaches and believes that Jesus Christ is the center of all biblical revelation. Christ is the center of God's revealed word. Every page of the Bible is either pointing to Christ, or reflecting back upon him.
Jesus Christ himself talked about his prophetic office. Matthew 11 has Christ declaring that he has come to reveal the Father. In Luke 22 he says that he came to do the Father's will. John 8 records that Jesus stated, "I do nothing on my own authority, but speak just as the Father taught me." All these statements show us that Jesus was fulfilling a prophetic office by showing us and revealing to us who the Father is and what his will for his people is.
Others in Scripture talked about Christ's prophetic office as well. Moses spoke of another prophet who God would raise up (Deut. 18:15). The Apostle Peter would use the words of Moses in his sermon in Acts 3: "Moses said, 'The Lord God will raise up for you a prophet like me from your brothers. You shall listen to him in whatever he tells you. And it shall be that every soul who does not listen to that prophet shall be destroyed from the people.'" Peter boldly declares that Jesus Christ is the prophet Moses spoke of, and that in Jesus Christ alone is salvation found.
Jesus Christ, therefore, is not merely a prophet, as many false religions would teach. He is the prophet. He is the prophet that all other prophets spoke of. He is the ultimate revelation of God's will, God's Word, God's plan for salvation, God's character. There is no prophet now apart from Jesus Christ, for no prophet could possibly reveal more or add to what Christ has already revealed to us in himself. It is because of this that the author of Hebrews would write, "Long ago, at many times and in many ways, God spoke to our fathers by the prophets, but in these last days he has spoken to us by his Son, whom he appointed the heir of all things, through whom also he created the world. He is the radiance of the glory of God and the exact imprint of his nature, and he upholds the universe by the word of his power. After making purification for sins, he sat down at the right hand of the Majesty on high..." Who would ever dare try to add to such a divine, such a complete, such a beautiful revelation of God!?