The deadliest war in history excluding World War II was a civil war in China in the 1850s in which the rebels were led by a man who thought he was the brother of Jesus Christ.
1 Therefore, having been justified by faith, we have[a] peace with God through our Lord Jesus Christ, 2 through whom also we have access by faith into this grace in which we stand, and rejoice in hope of the glory of God. 3 And not only that, but we also glory in tribulations, knowing that tribulation produces perseverance; 4 and perseverance, character; and character, hope. - Romans 5:1-4 NKJ