It shouldn’t come as a surprise to anyone that McCain isn’t popular among Christians. If it’s important that your candidate shares your faith, then McCain would be the least choice since he seems so uncomfortable discussing social and faith issues:

The Arizona senator is losing the Christian vote decisively to both Obama and Clinton, even though the poll was conducted as the recent firestorm over the Rev. Jeremiah Wright Jr. erupted.
If the general election were held today, McCain would lose the Christian vote to the Democratic nominee — 36 percent to 45 percent — with 19 percent of Christian voters currently undecided.
Among Protestants, McCain pulls even with the Democrats at 40 percent. But the Democrats have a whopping 32-point lead over McCain among Catholics.
Among white evangelical Protestants, McCain is doing better (51 percent to 28 percent), but clearly they have not rallied behind him at this point.
By contrast, the 2004 exit polls found that George W. Bush beat John Kerry among Protestants (59 percent to 40 percent), Catholics (52 percent to 47 percent), and white evangelical Protestants (78 percent to 21 percent).

As the poll demonstrates many Catholics and Evangelicals have moved to supporting the Democrats because they’ve decided to put the abortion issues aside (they believe him when he says that he’s post-partisan on this issue) and focus on other issues such as poverty, the environment and the Iraq war. That seems to be the position of Douglas Kmiec who was legal counsel to Presidents Reagan and George H.W. Bush. Kmiec, who is Catholic, sites those reasons for endorsing Obama in this excellent interview by God-o-Meter’s Dan Gilgoff. On why Obama’s abortion position didn’t hold him back from endorsing him:

And so at some point you have to decide whether the incidence of abortion will be more affected by the another conservative Republican appointing the right person to the Supreme court, and resolved as a legal issue, or by a candidate who wants to end the politics of division and who has a healthy responsibility for religion and its place in public thinking and public discourse. I came to the conclusion that his personal faith journey, which causes him to fully recognize how faith answers the hunger in the human soul, and his willingness to talk about self-responsibility, would make him mindful of opposing views on abortion.
[...]
It’s not the specific failure of this president or this administration, it’s the conclusion that trying to change the law on this topic [abortion] is a bit of fool’s game, that the thing that needs to be changed is more the heart of the individual person and the attitude of the larger culture. And that can hopefully be done by some of the things that Senator Obama talks about: the attitude of personal responsibility, of importance of the family, the well being of the culture, and quite frankly the economic policies that would affect the needs of the poor and the average American.

I think that a number of Evangelicals have come to the same conclusion (Douglas Goothuis calls it fetus fatigue). Even if Roe v. Wade was overturned, that wouldn’t change the hearts and minds of people who think abortion is OK and having it be legal and readily available for all these years has desensitized people to what they are doing. We need to focus on the issues surrounding abortion to make it unnecessary. I think it’s a compelling argument but I don’t think that Obama has the moral high ground to be the one to bring us together on this issue when he voted for what is essentially infanticide, which Kmiec calls a “mistake” (I haven’t seen Obama admit it was a mistake). My question to people who care about the abortion issue but support Obama or Clinton anyway because they see this as a social issue not a governmental issue is this: what makes you think Obama or Clinton won’t sign a bill funding abortions for those who can’t afford them?
Go read the rest of the article because it really does demonstrate the appeal of Obama for those who desire religion to take a more prominent role in this election and don’t see it happening with McCain.
The Democrats should be happy, they finally have the faith advantage they’ve been wanting since 2000. Let’s see if it does them any good.
BTW, as to Kmiec’s view of the war as a “preemptive war being contrary to the principles of just war” it should be noted that the war is no longer a preemptive war but an occupation and it’s about protecting the people of Iraq from al Qaeda and the armed Shiite militias. It’s about making sure that the Iraqis can defend themselves and that al Qaeda doesn’t set up a base of operations in which they can train jihadists. I’m sure there is nothing unbiblical about living up to our responsibility to not leave the Iraqi people in a precarious position. Christian charity would demand it.