John McCain is widely regarded as a "sensible" Republican who is "independent" of many traditional Republican constituencies. Neither view is correct: John McCain is not sensible when it comes to questions of church/state separation and, at least when it comes to the radical Christian Right, he isn't the least bit independent. McCain gladly repeats traditional Christian Nationalist lies about America being a "Christian Nation" and appears more than happy to abandon secular government. This makes John McCain about as dangerous to secular, civil government as any Republican candidate could be.
Many Americans believe the lies which Christian Nationalists have repeated so often. According to a survey done by the First Amendment Center, 55% of Americans think that the Constitution actually establishes America as a Christian Nation while 65% believe that America's founders intended America to be a Christian Nation. Rather than correct people and tell them the truth, John McCain simply nods and agrees with them:
A recent poll found that 55 percent of Americans believe the U.S. Constitution establishes a Christian nation. What do you think?
I would probably have to say yes, that the Constitution established the United States of America as a Christian nation. But I say that in the broadest sense. The lady that holds her lamp beside the golden door doesn't say, “I only welcome Christians.” We welcome the poor, the tired, the huddled masses. But when they come here they know that they are in a nation founded on Christian principles.
Source: Beliefnet, emphasis added
Notice that McCain isn't merely saying that America "is a Christian nation," but rather than the Constitution established America as a Christian Nation. Unlike many — if not most — of the people responding to the poll in question, we can be confident that McCain has carefully read the Constitution. Multiple times, I would hope.
John McCain must know, therefore, that the Constitution doesn't even mention Christianity, much less "establish" America as a Christian nation. The only time "establishment" is mentioned is to explicitly deny the government any authority to "establish" any religion. McCain must therefore know that what he said is false — and when you knowingly tell falsehoods, that's lying.
It would be true, of course, to say that America is "Christian" in the sense that most Americans are now and in the past have been Christians, but that's not what conservatives mean. To assert that America is a "Christian Nation" is to assert that America is "Christian" in some fundamental sense: that it's law, politics, government, or culture is necessarily Christian in nature. Religious conservatives want people to believe this because then, by defining what "true" Christianity is, they hope to define the nature of America itself - and do so in a way that excludes non-Christians, non-Christian ideas, and non-Christian institutions from full equality.
It's difficult to not to conclude, then, that John McCain is lying here. Granted, politicians lie quite a bit, but I think it may be taking that a few steps further when a politician lies about something like this. The most generous we can be is that he's lying in order to please the large numbers of Americans who answered the same way in this survey, but that's hardly a legitimate justification. Back when he was running for president in 2000, McCain accused leaders of the Christian Right of having a "corrupting influence on religion and politics." Today, he embraces the views, tactics, and leaders of the Christian Right.