Matthew 10:34

Think not ye that I am come to send peace on earth
The Jews had a notion of great outward peace and prosperity in the days of the Messiah; which was grounded on several prophecies of the Old Testament, not rightly understood by them; and the disciples of Christ had imbibed the same notion: wherefore our Lord thought fit to let them know the contrary; and that they must not expect outward ease and quiet, and worldly tranquillity would attend their ministry; for though he came to be a peace maker between God and sinners, by the blood of his cross; and was both the author and donor of spiritual peace to his people; and the Gospel he brought with him, and sent them to preach, was the Gospel of peace; which, accompanied with his power, would produce peace in the consciences of men, and be the means of cultivating and maintaining peace among the saints; yet "peace on earth" in a temporal sense, whether in the world in general, or in Judea in particular, must not be expected as the consequence of his coming; so far from it, that he subjoins,

I came, not to send peace, but a sword.
By the "sword" may be meant the Gospel, which is the means of dividing and separating the people of Christ from the men of the world, and from their principles and practices, and one relation from another; as also of divisions, discords, and persecutions arising from it: not that it was the intention and design of Christ, in coming into the world, to foment and encourage such things; but this, through the malice and wickedness of men, was eventually the effect and consequence of his coming; see ( Luke 12:51 ) where, instead of a "sword", it is "division"; because the sword divides asunder, as does the sword of the Spirit, the word of God.