Albert Barnes Commentary Mark 13:12

"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." — Mark 13:12 (ASV)

The brother shall betray, etc. The brother will treacherously give up his brother to be put to death, because of his attachment to Jesus. Through fear, in the hope of reward and the hatred of the gospel, he will overcome all the natural ties of brotherhood, and give up his own kindred to be burned or crucified. Perhaps nothing could more clearly show the dreadful evil of those times, as well as the natural opposition of the heart to the religion of Christ.