It turns out that the collected words of Abraham Lincoln are on line and searchable, and indeed there is no evidence that Lincoln made that rather pompous statement about being on God’s side so widely attributed to him–and recently alluded to by Sarah Palin. But my colleague Ron Spencer has called my attention to a relevant statement by Lincoln–one that shows, to my mind, just the way for a president to relate his decision making to divine intentions.
It came about on September 13, 1862, when Lincoln met with a group of Chicago clergy who were urging him to free the slaves. In his remarks, which were published ten days later in the Chicago Tribune, Lincoln made clear, in his characteristically shrewd and droll way, that the only way to discern the will of Providence in so difficult matter was to make the wisest secular judgment he could manage. On the issue of whose side God might be on, he notes that the religious on either side of the question couldn’t both be right, and that both might be wrong; and suggested that the Southern troops seemed to be praying more earnestly than the Northern ones that God was on their side:

The subject presented in the memorial is one upon which I have thought much for weeks past, and I may even say for months. I am approached with the most opposite opinions and advice, and that by religious men, who are equally certain that they represent the Divine will. I am sure that either the one or the other class is mistaken in that belief, and perhaps in some respects both. I hope it will not be irreverent for me to say that if it is probable that God would reveal his will to others, on a point so connected with my duty, it might be supposed he would reveal it directly to me; for, unless I am more deceived in myself than I often am, it is my earnest desire to know the will of Providence in this matter. And if I can learn what it is I will do it! These are not, however, the days of miracles, and I suppose it will be granted that I am not to expect a direct revelation. I must study the plain physical facts of the case, ascertain what is possible and learn what appears to be wise and right. The subject is difficult, and good men do not agree. For instance, the other day four gentlemen of standing and intelligence (naming one or two of the number) from New York called, as a delegation, on business connected with the war; but, before leaving, two of them earnestly beset me to proclaim general emancipation, upon which the other two at once attacked them! You know, also, that the last session of Congress had a decided majority of anti-slavery men, yet they could not unite on this policy. And the same is true of the religious people. Why, the rebel soldiers are praying with a great deal more earnestness, I fear, than our own troops, and expecting God to favor their side; for one of our soldiers, who had been taken prisoner, told Senator Wilson, a few days since, that he met with nothing so discouraging as the evident sincerity of those he was among in their prayers.

Spencer points out that these remarks constitute the first public claim by Lincoln that he possessed, as commander in chief, the power to emancipate the slaves. And shortly thereafter, he did.