Lincolns Battle with God: A President Struggle with Faith and What It Meant for America by Stephen Mansfield. Just wrote this review on Amazon:
Mansfield does an admirable job of presenting the evidence for Abraham Lincoln's Christian faith as far as the historical evidence will support such a claim to faith. The portrait that emerges is arguably of a Lincoln falling short of an evangelical faith in that he is not known to have believed in eternal punishment, but also of a Lincoln having a strong general (liberal if you will) Christian faith in the Resurrection of the dead, Christ as Savior of the World, and God as sovereign over the events of history.
Lincoln seems to have been exposed to the best and worst in Christianity of his day by being strengthened in his faith through the writings of Presbyterian Pastor Reverend James D. Smith of Springfield, whose apologetic writings contained in The Christian's Defence, Lincoln is known to have read. At the same time Lincoln was exposed likely exposed to some of the church pettiness of his day. As he attended Smith's church in Springfield, the Presbyterian session was charged at one point with investigating a church member for the sin of dancing. (Lincoln and his wife had met at a dance.) Even in death, Lincoln couldn't escape the cultural bias of his day. Pastors lamented the fact that his death took place in a theater. Or in the words of one Presbyterian Pastor, "the theater is one of last places to which a good man should go."
Despite many challenges, Lincoln's faith eventually took form. Perhaps its strongest statement is Lincoln's Second Inaugural Address. Here Lincoln lays out an overwhelming case for God's sovereignty in history and the case against slavery, but he charges both the North and South with the collective crime of slavery that God must judge. Lincoln also lays out a Scriptural philosophy of history in which God is portrayed as allowing the crimes of humanity to go so far, but no further, until evil has reached its fullness and is judged.
This is a good book. It's made that much more enjoyable in that Mansfield is able to keep things complete, yet brief. And even while being brief provide several mini-histories of various topics. We see the sad picture for example of Mrs. Lincoln's interest in spiritualism after her son's death, even as her husband is turns closer to his Christian faith as a way of coping with his grief. More examples could be mentioned. But it suffices to say that this is a book that is well worth it.