Matthew 10:21 - Albert Barnes' Notes on the Bible

And the brother shall deliver up the brother ... - Were there no evidence that this had been done, it would scarcely be “credible.” The ties which bind brothers and sisters, and parents and children together, are so strong that it could scarcely be believed that division of sentiment on religious subjects would cause them to forget these tender relations. Yet history assures us that this has been often done. If this be so, then how inexpressibly awful must be the malignity of the human heart by nature against religion! Nothing else but this dreadful opposition to God and his gospel ever has induced or ever can induce people to violate the most tender relations, and consign the best friends to torture, racks, and flames. It adds to the horrors of this, that those who were put to death in persecution were tormented in the most awful modes that human ingenuity could devise. They were crucified; were thrown into boiling oil; were burned at the stake; were roasted slowly over coals; were compelled to drink melted lead; were torn in pieces by beasts of prey; were covered with pitch and set on fire. Yet, dreadful as this prediction was, it was fulfilled; and, incredible as it seems, parents and children, husbands and wives, were found wicked enough to deliver up each other to these cruel modes of death on account of attachment to the gospel. Such is the opposition of the heart of man to the gospel! That hostility which will overcome the strong ties of natural affection, and which will be satisfied with nothing else to show its power, can be no slight opposition to the gospel of God.