I've been pretty busy teaching two intensive summer courses for the last few weeks, and I didn't have easy access to a computer for a good part of that time because Dell's next-day contract isn't exactly giving me next-day service due to some backlog problems (I still don't have full resolution from a problem that began something like 13 days ago.) But I did catch some people commenting that President Obama said that the U.S. would be one of the largest Muslim countries in the world if you just counted all the Muslims in the U.S., and I did see some people juxtaposing that comment with his claim during the election that the U.S. isn't a Christian country, claiming that he had contradicted himself.
There is a real tension between what he's doing with those two statements, but I don't think he contradicted himself. It turns out that one of his statements is hopelessly false. According to a Pew study, Muslims are about .6% of the U.S. population, which brings the total to less than 2 million. It seems France and Germany have more Muslims than the U.S. does, and most Muslim states are higher than that also. See Mollie Hemingway for some sources and some graphical presentations of the information. But the statements can be consistent even if one of them is false.
We need to ask first what it takes for a country to be Christian or Muslim. 1. Is a country a Christian country merely because its majority is Christian and its traditions are largely influenced by Christian traditions? 2. Or does there have to be an official declaration of Christianity as the nation's religion? 3. Or is that even enough, given that Christianity itself is a decidedly non-nationalizing religion, with strong resistance to seeing faith in the nationalized way that old-covenant religion in Israel was. The expansion to include all nations resists the very possibility of a Christian nation, according to Christian theology.
But what many people mean by using the adjective 'Christian' in this context is not any such thing but more that the government's structure, the legal tradition's views of human rights and assumptions of common law, and the nation's broader traditions are Christian-influenced in a strong enough way.
You have a very different situation with Islam. A nation can be Muslim in the weaker sense. It can also be Muslim in the second sense of being an officially-Muslim government, and in fact most nations that are Muslim in the first sense are also Muslim in the second. (I believe the only ones that haven't been have been controlled by a minority hierarchy of non-Muslims). But Islam explicitly affirms the third kind of being a Muslim nation, something Christianity never condones for itself. So that does change things, I think. It can much more easily be the case that a nation is unambiguously Muslim than it can be for a nation to be unambiguously Christian (in fact it's impossible for Christianity).
But will this help resolve the tension between the two Obama statements? I doubt his understanding of biblical theology is sufficient for him to come up with the view that it's impossible for a nation to be Christian in the third sense, but it's quite plausible that he meant the second sense when he said that the U.S. is not a Christian nation. It's pretty obviously not true if he meant it in the first sense, especially with his fairly broad sense of what it means to be a Christian. [And his view of Christianity is broader than mine, since he does consider himself a Christian, and I find it hard to include him given his denial of any afterlife, his conception of prayer as talking to himself, his reducing of the Holy Spirit to anyone's coming to see something that's true, and his conception of Jesus as merely bridging the God-human gap rather than having dealt with a serious problem of human sin interfering with any connection with God's holy nature. (See my Is Barack Obama an Evangelical? for further details on all that.) So with a broader conception of what counts as Christian, the numbers of Christians and the influence of Christianity in the U.S. will only appear to be stronger to someone like him than it would to someone like me with my more restrictive views of what is genuinely Christian.]
What about his statement about the U.S. being one of the largest Muslim countries if you only counted the Muslims. Even though the statement isn't even close to being true, I'm interested in what he meant to see if it's consistent with his statement about the U.S. not being a Christian nation. If he meant it in the second or third way, it's obviously false. I think he must have meant it in the first way. But saying something like that and meaning it in the first sense with Islam is perfectly consistent with resisting something along the same lines about Christianity and meaning it in the second sense. So I don't think his two statements are actually at odds, at least in terms of the consistency of the two things he meant with each statement.
Nevertheless, there might well be a tension between the pragmatic purpose of what he's trying to do in one case and the pragmatic purpose he's trying to achieve in the other. In the later case, he was looking toward a major speech trying to win over the Muslim world, so he wanted his audience in that speech to see that he was being positive about Muslim participation in American society. What was he doing in the first case? He was probably trying to satisfy the left's continued insistence that the religious right shouldn't control policies that people might disapprove of if they have other religious convictions or none at all. So the surface motivation is to be inclusive, a similar purpose to his later claim about Islam. Nevertheless, I do think the statement he made, in the context of why people do claim that this is a Christian nation, serves to send a message that Christian concerns are not to be included at the table when discussing certain kinds of policies. To the extent that that's true, I do think his statement serves an exclusionary purpose with socially-conservative religious voters, who were by and large turned off by his statement.
What he literally meant shouldn't have offended by it, but what he was trying to accomplish certainly does treat their concerns as unimportant. For that reason, I don't think those who are criticizing him for being inconsistent with these two statements are entirely wrong. There is something behind the first statement that is at odds with what he's trying to do with the second, at least if he wants to treat all religious expressions as legitimate and positive, which he at least says he wants to do.