Obama’s inaugural address was brimming with religious references.

“We remain a young nation, but in the words of Scripture, the time has come to set aside childish things….”
“This is the source of our confidence — the knowledge that God calls on us to shape an uncertain destiny….”
“With eyes fixed on the horizon and God’s grace upon us, we carried forth that great gift of freedom and delivered it safely to future generations….”

But the most consequential faith-based line may have been his invitation to non-belielvers.

We are a nation of Christians and Muslims, Jews and Hindus — and non-believers

I have not so far been able to find any other references to non-believers in an inaugural address.
Non-believers are one of the largest political constituencies that politiians rarely want to acknowledge. A recent Pew Center paper reports that while 16.1% of Americans say they’re religiously unaffiliated, not a single member of Congress identifies that way. Basically, Christians, Mormons and Jews are, statistically, over-represented and unaffiliateds, agnostics and atheists are underrepresented.
Not surprisingly, they greeted Obama’s inaugural declaration with some surprise and joy. “In his Inaugural Address today, President Barack Obama finally did what many before him should have done, rightly citing the great diversity of Americans as part of the nation’s great strength and including ‘non-believers’ in that mix,” said Ed Buckner of American Atheists. “His mother would have been proud, and so are we. ”