It's a lovely post with a lovely conclusion:
"It is always easier to explain why Washington, Jefferson, and Lincoln belong on Mount Rushmore. Lincoln is America’s Christ. And Washington plays God the Father to Lincoln’s martyred savior. Which leaves to Jefferson the role of Holy Spirit: just so, as the author of the Declaration of Independence, the deeply flawed Jefferson nevertheless carried enough divine fire to channel into words the nation’s enlivening ideal of equality and natural right.
With such an established trinity, what need for a fourth figure? If we can see elements of the godly in each of Washington, Jefferson, and Lincoln, what can we do with the rather thoroughly earthly Roosevelt? But perhaps that is the point. Alongside gods humanity also has a place, and a man who did so much to make daily life in America a little better, and to create the expectation that daily life in America must be better, belongs there."
It's worth a read...