Obama's Lincoln connection

What does it mean that Obama is to be sworn into office on Abraham Lincoln's Bible?

Lincoln is known as a religious skeptic, among other views on religion. I just wonder if Obama, being the closet-atheist I suspect, would deliberately choose Lincoln's Bible to echo this sentiment.

It was the Declaration of Independence, rather than the Bible, that Lincoln most relied on in order to oppose any further territorial expansion of slavery. He saw the Declaration as more than a political document. To him, as well as to many abolitionists and other antislavery leaders, it was, foremost, a moral document that had forever determined valuable criteria in shaping the future of the nation. [Source.]

Perhaps Obama should be sworn in on the Declaration if Independence, then?