From Charles Hodge's Systematic Theology, Vol. 3
The proposition that the United States of America are a Christian and Protestant nation, is not so much the assertion of a principle as the statement of a fact. That fact is not simply that the great majority of the people are Christians and Protestants, but that the organic life, the institutions, laws, and official action of the government, whether that action be legislative, judicial, or executive, is, and of right should be, and in fact must be, in accordance with the principles of Protestant Christianity...
It is in accordance with analogy. If a man goes to China, he expects to find the government administered according to the religion of the country. If he goes to Turkey, he expects to find the Koran supreme and regulating all public action. If he goes to a Protestant country, he has no right to complain, should he find the Bible in the ascendancy and exerting its benign influence, not only on the people but also on the government.
The principle that the religion of a people rightfully controls the action of the government, has of course its limitation. If the religion itself be evil and require what is morally wrong, then as men cannot have the right to act wickedly, it is plain that it would be wrong for the government to conform to its requirements. If a religion should enjoin infanticide, or the murder of the aged or infirm, neither the people nor the government should conform their conduct to its laws. But where the religion of a people requires nothing unjust or cruel or in any way immoral, then those who come to live where it prevails are bound to submit quietly to its controlling the laws and institutions of the country.
The principle contended for is recognized in all other departments of life. If a number of Christian men associate themselves as a manufacturing or banking company, it would be competent for them to admit unbelievers in Christianity into their association, and to allow them their full share in its management and control. But it would be utterly unreasonable for such unbelievers to set up a cry of religious persecution, or of infringement of their rights and liberty, because all the business of the company was suspended upon the Lord’s Day. These new members knew the character and principles of those with whom they sought to be associated. They knew that Christians would assert their right to act as Christians. To require them to renounce their religion would be simply preposterous.
When Protestant Christians came to this country they possessed and subdued the land. They worshipped God, and His Son Jesus Christ as the Saviour of the world, and acknowledged the Scriptures to be the rule of their faith and practice. They introduced their religion into their families, their schools, and their colleges. They abstained from all ordinary business on the Lord’s Day, and devoted it to religion. They built churches, erected school-houses, and taught their children to read the Bible and to receive and obey it as the word of God. They formed themselves as Christians into municipal and state organizations. They acknowledged God in their legislative assemblies. They prescribed oaths to be taken in His name. They closed their courts, their places of business, their legislatures and all places under the public control, on the Lord’s Day.
They declared Christianity to be part of the common law of the land. In the process of time thousands have come among us, who are neither Protestants nor Christians. Some are papists, some Jews, some infidels, and some atheists. All are welcomed; all are admitted to equal rights and privileges. All are allowed to acquire property, and to vote in every election, made eligible to all offices, and invested with equal influence in all public affairs. All are allowed to worship as they please, or not to worship at all, if they see fit. No man is molested for his religion or for his want of religion. No man is required to profess any form of faith, or to join any religious association. More than this cannot reasonably be demanded. More, however, is demanded. The infidel demands that the government should be conducted on the principle that Christianity is false. The atheist demands that it should be conducted on the assumption that there is no God, and the positivist on the principle that men are not free agents. The sufficient answer to all this is, that it cannot possibly be done.
The demands of those who require that religion, and especially Christianity, should be ignored in our national, state and municipal laws, are not only unreasonable but they are in the highest degree unjust and tyrannical.