Blessed are the peacemakers, For they shall be called sons of God.
Matthew 5:9

Jesus said these words. He also said these words:

"Do not think that I have come to bring peace to the earth. I have not come to bring peace, but a sword. For I have come to set a man against his father, and a daughter against her mother, and a daughter-in-law against her mother-in-law. And a person's enemies will be those of his own household. Whoever loves father or mother more than me is not worthy of me, and whoever loves son or daughter more than me is not worthy of me. Matthew 10:34-37

Did He contradict Himself? Not at all. Truth is worth fighting for when necessary!

Parents must train their children in the Lord, even when the children resist. In such cases, coercion (force) must be applied for the sake of truth (Ephesians 6:4, Proverbs 13:24).

The church must sometimes speak out against serious error for the sake of truth. This can even escalate into “disfellowshipping” (expelling) one who disrupts the church with sin or other serious error (1 Corinthians 5:1-11, Titus 3:10-11).

The state is commissioned by God to punish evildoers for the sake of law abiding citizens (Romans 13:4).

Governments must sometimes wage war to halt forces that threaten the peace of its citizens (Romans 13:4).

Sometimes force is necessary to maintain peace instead of appeasing sin and other error.

Without any doubt, the greatest demonstration of this truth was when God the Father poured out His holy and just wrath on Jesus to secure forgiveness of our sins.