The next time you get into a debate with a fundamentalist who insists that this is a Christian nation, ask them which denominations they consider Christian. Do they consider Catholics Christians? You might be surprised to find many do not. Likewise for many of the more liberal sects. When you go through the list, you'll find that to many fundamentalists (Church of Christ, Nazerene, Pentecostal, Methodists), a very small minority qualify as Christians. Yet when wanting to persuade people that we are a christian nation, they include all those liberal sects. They use a double standard and should be called on it. The only way they can rightly claim the nation is majority Christian, they have to grant that status to Catholics and Episcopalians and all the other liberal sects.
Hat tip to Blaidd Drwg who put it this way:
Since most of the "mainstream" churches tend to define ALL the other sects (of Christendom) as 'non-Christian', it makes one wonder if we are REALLY predominately Christian as a nation. eg. the Holiness/Charismatic/Apostolic folks define Lutherans, Methodists, Presbyterians, and even Baptists as 'fallen', 'backsliding', and even 'demonic' - and don't even mention the Catholics, "everybody knows" they are the very spirit of the AntiChrist. Thus, since ~5% of the nation belongs to the B/C/A churches, then by definition (theirs), we are NOT an overwhelmingly Christian nation, and Christianity is, in fact, a minority smaller than 'teh gay'.