You can't study church-state separation issues without studying civil religion and it is very, very hard to study civil religion without taking a look at the whole issue of how presidents talk about faith and, in particular, God. I was already thinking about this issue when I wrote my Scripps Howard News Service column this week, which was a follow-up, sort of, to the whole Mike Huckabee "vertical" credo flap (with insights from Mike Gerson about the whole issue of "soaring" language in political rhetoric). While researching that column, I read the whole sermon -- call it what it is -- by Barack Obama during his Jan. 20 stop in the pulpit at Ebenezer Baptist Church in Atlanta, where he helped that congregation celebrate the legacy of the Rev. Martin Luther King, Jr.

What can you say? This is how the text starts:

The Scripture tells us that when Joshua and the Israelites arrived at the gates of Jericho, they could not enter. The walls of the city were too steep for any one person to climb; too strong to be taken down with brute force. And so they sat for days, unable to pass on through.

But God had a plan for his people. He told them to stand together and march together around the city, and on the seventh day he told them that when they heard the sound of the ram's horn, they should speak with one voice. And at the chosen hour, when the horn sounded and a chorus of voices cried out together, the mighty walls of Jericho came tumbling down.

There are many lessons to take from this passage, just as there are many lessons to take from this day. ...

Needless to say, there was a political message in that speech as well as a religious one. That's how civil religion works.

And what, you say, about Godtalk on the other side of the church aisle these days? Can Republicans be as blunt, in the current marketplace?

Maybe not. Someone, somewhere, really needs to write a doctoral dissertation on how the faith language of President George W. Bush has evolved while in office. You could spend a chapter parsing the quotes in the following Washington Post story by Michael Abramowitz in which the president has some rather blunt talk in Baltimore with former prisoners about the subject of substance abuse and addiction. Here's the lede:

President Bush plopped himself into a chair between two former prisoners, Thomas Boyd and Adolphus Moseley, and asked to hear how their lives had changed. But first, he wanted them to know something about him: "I understand addiction," he said, "and I understand how a changed heart can help you deal with addiction."

In other words, this was a chance for Bush to -- as church people say -- "offer his testimony." And here is what went down:

"Why were you in jail, if you don't mind me asking?" Bush asked Moseley, a gregarious 42-year-old who replied that he served time for cocaine possession. "It's just one of those things that you need to put behind you," he told the president.

Moseley told Bush they could use more such mentoring and counseling programs on the west side of Baltimore, and Bush replied: "There are programs like that all over the city; they are called churches."

"They are not sincere, like Jericho," Moseley replied, seeming to take Bush a bit aback.

"My only point to you is there are a lot of faith-based organizations that exist to help deal with very difficult problems," Bush said. "It starts with the notion that there is a higher power that will help people change their thinking.

"It's very important for everybody to understand that there is a commonality, that we all have to deal with the same problems in different ways," Bush said. "First is to recognize that there is a higher power. At least that helped in my life -- it helped me quit drinking."

Moseley interjected, "That's right, there is a higher power."

Obviously, Bush is using the language of recovery groups such as Alcoholics Anonymous. This is "step two," "higher power" talk.

Still, it is interesting to note how careful the president was to avoid God language. It was, well, a flashback to the cautious style of the Bush family in general. And that reminds me of my all-time favorite Bush family anecdotes, which focuses on a campaign appearance by George H.W. Bush. Enjoy.

On one campaign stop, he was asked what he thought about as he floated alone in the Pacific Ocean after his plane was shot down during World War II. His response was chilly: "Mom and Dad, about our country, about God ... and about the separation of church and state."

There you go. That'll preach.