This is worth a close read.
This CNN blog post explains how, historically, there is only a very loose correlation between a president’s personal religious convictions and their effectiveness as a national leader. Some of our most revered presidents have been very religiously unorthodox (e.g. Thomas Jefferson), and some of the most religiously devout have been the most violent and brutal (e.g. Andrew Jackson). Finally, it discusses President Obama’s personal Christian religious convictions: