As I explain in my book Abraham Lincoln and the Bible: A Complete Compendium (published April 2023 by Southern Illinois University Press), by the time Abraham Lincoln became president, he had developed a strong reliance on the Bible for personal direction, as well as political leadership. On September 7, 1864 Lincoln described the Bible as “the best gift God has given to man.”(1) In the summer of 1864 Lincoln told his closest lifelong friend Joshua Speed (who was a self-proclaimed skeptic) that he should “take all of the Bible upon reason that he can, and the balance on faith.”(2)

Lincoln read the Bible frequently while he was president, and often quoted or alluded to scripture to support moral arguments, letters, and proclamations he was making to the northern people. The following is a prime example of how he directly quoted or alluded to the Bible as president during the Civil War. It is an excerpt from a letter he wrote to George B. Ide, James R. Doolittle, and A. Hubbell on May 30th, 1864, thanking them for their support of the abolition of slavery:

[Lincoln wrote] Indeed, it is difficult to conceive how it could be otherwise with any one professing Christianity, or even having ordinary perceptions of right and wrong. To read in the Bible, as the word of God himself, that “In the sweat of thy face shalt thou eat bread”] [direct KJV quote of Genesis 3:19], and to preach there-from that, “In the sweat of other men’s faces shalt thou eat bread,” to my mind can scarcely be reconciled with honest sincerity. When brought to my final reckoning [allusion to 2 Corinthians 5:10], may I have to answer for robbing no man of his goods [allusion to 1 Samuel 12:3]; yet more tolerable even this, than for robbing one of himself, and all that was his. When, a year or two ago, those professedly holy men of the South, met in the semblance of prayer and devotion, and, in the name of Him who said “As ye would all men should do unto you, do ye even so unto them” [direct quote of Matthew 7:12] appealed to the Christian world to aid them in doing to a whole race of men, as they would have no man do unto themselves, to my thinking, they contemned and insulted God and His church, far more than did Satan when he tempted the Saviour with the Kingdoms of the earth [allusion to Matthew 4:8–10]. The devil’s attempt was no more false, and far less hypocritical. But let me forbear, remembering it is also written “Judge not, lest ye be judged” [direct quote of Matthew 7:1].(3)