Going into this election, Republicans owned most of the seriously devout voters. John Green, who studies religious voting patterns for the Pew Forum on Religion & Public Life, says that ownership dates back 30 years.

But we saw a shift last month, and an important one. Barack Obama narrowed the “God gap” between the parties. The data’s still coming in, but here’s what I mean:

– Public Religion Research’s post-election poll shows Obama sharply improved on perceptions of the Democrats’ friendliness to religion. Dr. Robert Jones, who heads the group, reports that 54 percent of voters saw Obama as friendly to religion, a 16 percent increase for Democrats from 2004.

True, 58 percent of respondents saw John McCain as friendly to religion. And Green says Republicans still did well with mainline Protestants (like Methodists, Presbyterians and Episcopalians).

Earlier this year, I reported Democrats could crack deeper into this mostly Republican group. That didn’t happen, but Obama didn’t lose ground among mainliners. That’s significant, as Democrats have stopped the bleeding.

Also revealing is that more evangelicals are giving the new president a shot. About 40 percent say he shares their values and is friendly to religion. That number’s impressive when you consider how reliably Republican most evangelicals have been.

Going forward, here’s what this shift means:

– The Reinhold Niebuhr-reading, churchgoing Democrat has an opening with religious voters. He especially has religious progressives and black churchgoers at his side. Many people of faith are looking for the common good, even though they didn’t vote for him.

But what does he do with this goodwill? He’s on a tricky slope.

Politicians must engender hope, which Obama has proven he’s good at doing. So good that some will be so swept up by his “Yes, We Can” rhetoric that they may be ready to march into some new millennium. That said, he risks disillusioning his followers if he comes across too idealistic.

“Texas Faith” panelist Joe Clifford, who also is my Presbyterian minister, makes a good point: “If we think we’re capable of fixing the world, we become blind to our sin.”

Digging into Niebuhr could help Obama find a sense of balance. He once told New York Times columnist David Brooks that he liked reading the Rev. Niebuhr, the late Protestant theologian and author.

That’s encouraging because the thinker occupied an important piece of the intellectual landscape in the last century. He stood against both the cynics of the Depression/World War II years, who thought the world was too flawed to improve it, and his fellow liberals of the 1930s, who thought mankind was progressing toward a heavenly city.

The way forward for Obama lies in blending idealism and realism. That’s not always easy. It means embracing “yes” as he tries to reduce poverty, global warming and abortion, while also being honest about the limits of the human condition.

Here’s why it matters to pay attention to the closing of the “God gap”:

– Understanding the direction of our culture and politics increasingly requires us to grasp the contours of religious belief. The values of the devout here and abroad inevitably shape their views of the larger world, as former State Department diplomat Thomas Farr’s writes perceptively in his new book, World of Faith and Freedom.

That’s why I tried this year to understand and interpret how people of various faith traditions viewed our presidential race. Evangelicals, mainline Protestants and Pentecostals were particularly on my radar. They either have been driving elections (evangelicals and mainline Protestants) or are emerging as key swing voters (Pentecostals).

Barack Obama made impressive inroads among some of them. Now, we will see what he will do with that. They’re looking to him for leadership, and his party has plenty riding on him finding the balance between hope and reality.

William McKenzie is an editorial columnist for The Dallas Morning News.