The question cannot be answered with a simple “yes” or “no” until we define more carefully what we mean by “a Christian nation.” That is one reason why people sometimes become so upset about this question—different people have different meanings in mind for the phrase “a Christian nation,” and therefore they can end up talking about different things but using the same words and just misunderstanding one another.
Here are several meanings one can attach to the phrase “a Christian nation,” together with an answer to the question that varies according to each meaning:
(1) Is Christian teaching the primary religious system that influenced the founding of the United States? Yes, it is.
(2) Were the majority of the Founding Fathers of the United States Christians who generally believed in the truth of the Bible? Yes, they were.
(3) Is Christianity (of various sorts) the largest religion in the United States? Yes, it is.
(4) Did Christian beliefs provide the intellectual background that led to many of the cultural values still held by Americans today? (These would include things such as respect for the individual, protection of individual rights, respect for personal freedom, the value of hard work, the need for a strong national defense, the need to show care for the poor and weak, the value of generosity, the value of giving aid to other nations, and respect for the rule of law.) Yes, Christian beliefs have provided much of the intellectual background for many of these and other cultural values.
(5) Was there a Supreme Court decision at one time that affirmed that the United States is a Christian nation? Yes, there was, but that wasn’t the issue that was under dispute in the case. It was in an 1892 decision, Church of the Holy Trinity v. the United States, 143 US 457 (1892). The ruling established that a church had the right to hire a minister from a foreign nation (England), and thus the church was not in violation of an 1885 law that had prohibited hiring “foreigners and aliens … to perform labor in the United States.” The court’s argument was that there was so much evidence showing the dominant “Christian” character of this nation that Congress could not have intended to prohibit churches from hiring Christian ministers from other countries. It seems to me that here the Supreme Court was arguing that the United States is a “Christian nation” according to meanings (3) and (4) above. There is a long history of significant Christian influence on the United States.
(6) Are a majority of people in the United States Bible-believing, evangelical, born-again Christians? No, I do not think they are. Estimates range from 18 to 42% of the US population who are evangelical Christians, and I suspect a number around 20% is probably more nearly correct. In a 2005 poll, Gallup, after doing a survey designed to find how many Americans had true evangelical beliefs, came up with a figure of 22%.6 In addition, there are many conservative Roman Catholics who take the Bible plus the official teachings of the Catholic Church as a guide for life, and a significant number of them have a personal trust in Jesus Christ as their Savior. But even if these groups are added together, it does not constitute a majority of people in the United States.
(7) Is belief in Christian values the dominant perspective promoted by the United States government, the media, and universities in the United States today? No, it is not.
(8) Does the United States government promote Christianity as the national religion? No, it does not.
(9) Does a person have to profess Christian faith in order to become a US citizen or to have equal rights under the law in the United States? No, certainly not. This has never been true. In fact, the Constitution itself explicitly prohibits any religious test for public office:
No religious test shall ever be required as a qualification to any office or public trust under the United States (Article VI, section 3).
In conclusion, how can we answer the question, “Is the United States a Christian nation?” It all depends on what someone means by “a Christian nation.” In five possible meanings, the answer is yes. In four other possible meanings, the answer is no. Because there are that many possible meanings in people’s minds (and possibly more that I have not thought of), I do not think the question is very helpful in current political conversations. It just leads to arguments, misunderstanding, and confusion. The same points that a speaker wants to make with this claim can be made more clearly, without causing confusion, in terms of one or more of the expanded meanings that I have listed above.
Wayne Grudem, Politics – According to the Bible, 64-65.