The Barna Group is known for its precision in tracking the preferences of religious groups, especially Evangelicals. The organization today released its latest election survey, finding that Obama is within the margin of error with McCain among self-described Evangelicals and leads across other major faith groups, though this lead has slipped somewhat over the past few months. As I've noted, McCain appears to be using strong religious imagery in his advertisements as a "Left Behind" strategy to shore up his support among Evangelicals. Obama's faith based strategy likely aims to capture a Clintonesque 30% of the Evangelical vote, a proportion that is likely to put him over the top in November's general election.

From the survey:

One of the most frequently reported on groups of voters is evangelicals. Most media polls use a simplistic approach to defining evangelicals, asking survey respondents if they consider themselves to be evangelical. Barna Group surveys, on the other hand, ask a series of nine questions about a person's religious beliefs in order to determine if they are an evangelical. The differences between the two approaches are staggering.

Using the common approach of allowing people to self-identify as evangelicals, 40% of adults classify themselves as such. Among them, 83% are likely to vote in November. Among the self-reported evangelicals who are likely to vote, John McCain holds a narrow 39% to 37% lead over Sen. Obama. Nearly one-quarter of this segment (23%) is still undecided about who they will vote for.

Using the Barna approach of studying people's core religious beliefs produces a very different outcome. Just 8% of the adult population qualifies as evangelical based on their answers to the nine belief questions. Among that segment, a significantly higher proportion (90%) is likely to vote in November, and Sen. McCain holds a huge lead (61%-17%) over the Democratic nominee. Overall, just 14% of this group remains undecided regarding their candidate of choice...

For the most part, the various faith communities of the U.S. currently support Sen. Obama for the presidency. Among the 19 faith segments that The Barna Group tracks, evangelicals were the only segment to throw its support to Sen. McCain. Among the larger faith niches to support Sen. Obama are non-evangelical born again Christians (43% to 31%); notional Christians (44% to 28%); people aligned with faiths other than Christianity (56% to 24%); atheists and agnostics (55% to 17%); Catholics (39% vs. 29%); and Protestants (43% to 34%). In fact, if the current preferences stand pat, this would mark the first time in more than two decades that the born again vote has swung toward the Democratic candidate.

However, while there has been little movement since the beginning of June among most voting segments (such as ethnic groups, age groups, or geographic slices), there has been substantial churn among religious segments. During the past two months, Sen. Obama's lead has eroded substantially among non-evangelical born again Christians (a decline of nine points); active Christians (a 20-point drop); Protestants (down 13 points); and Catholics (down 11 points).

While some Christian voters seem to be questioning their early support for Obama, the McCain candidacy does not seem to be gaining momentum among evangelicals. Since June, the current level of support Sen. McCain has among evangelical voters has declined significantly (dropping from 78% to 61%).