Let us consider each of these passages within its respective and immediate context.
The former is from the book of Isaiah. Sweeping across seven centuries of Hebrew history, the man of God prophetically declares the following concerning Jesus of Nazareth:
“For unto us a child is born, unto us a son is given; and the government shall be upon his shoulder: and his name shall be called Wonderful, Counsellor, Mighty God, Everlasting Father, Prince of Peace” (Isa. 9:6).
In this text, the Son of God is characterized in several illustrious ways, one of which is by the phrase “Prince of Peace.” The expression embraces several important ideas.
Jesus is the avenue by which human beings, alienated from the Father by their sins, may enjoy reconciliation, hence, be at peace with their Creator (Rom. 5:1; Eph. 2:13-14; Col. 1:20).
Knowing that we are on peaceable terms with the Lord, Christians are blessed with an inner peace, a tranquility of spirit, that allows us to live a contented life, even when the world around him is mad (Phil. 4:7).
Christ also provides for his people the motive to work for harmony among various cultures of men who, by longstanding tradition, are hostile to one another (e.g., the Jews and the Arabs — see Rom. 12:18; Heb. 12:14; cf. Lk. 2:14 — ASV, ESV).
In view of these facts, it should be no surprise that Jesus Christ should be designated as “Prince of Peace.”
The latter text, however, is perhaps more challenging. Here are the intriguing words from the Savior.
“Think not that I came to send peace on the earth: I came not to send peace, but a sword. For I came to set a man at variance against his father, and the daughter against her mother, and the daughter in law against her mother in law: and a man’s foes shall be they of his own household. He who loves father or mother more than me is not worthy of me; and he who loves son or daughter more than me is not worthy of me” (Mt. 10:34-37).
This text comes more sharply into focus when one recognizes the idiomatic language that is employed for the sake of forcefulness.
This passage is designed to emphasize the consequences that could follow when one commits to an unqualified loyalty to the Son of God.
Jesus was sending the twelve disciples on a preaching tour to the “lost sheep of the house of Israel” (Mt. 10:6). He warned them of the dangers of rejection; they would be like “sheep in the midst of wolves” (Mt. 10:16). The apostles would be opposed by political dignitaries, and even family members would react against them with violence.
“And brother shall deliver up brother to death, and the father his child: and children shall rise up against parents, and cause them to be put to death” (Mt. 10:21).
The cause of truth is so great and Christ’s mission and message are so vital, that no sacrifice is too great to make. Eternity is in view!
Thus, employing vivid imagery (not uncommon in biblical literature), the Savior, substituting the active voice for the passive (thus stressing the permissive will of God) declares that he is “send[ing]” a sword (of demanding dedication) that will, in many instances, separate the dearest of loved ones.
It is not that the “Prince of Peace” actively desires such fragmentation, but that such inevitably will result as the consequence of unqualified dedication to him.
When the foregoing facts are understood, there is absolutely no conflict between Isaiah 9:6 and Matthew 10:34ff.