There is an extant opinion that the influence of religious belief on legislation should be discouraged. The notion is that religion should be a totally private affair, and should never affect public policy. But an attentive reading of the Declaration of Independence reveals that this opinion is based on an idea of the separation of Church and State divorced from the context of its origin.
Of course, no decision of the United States Supreme Court has ever turned on the Declaration of Independence. That is as it should be, because the Declaration is not law. It is an enunciation of the grounds for our separation from Great Britain and the founding of the nation. That doesn’t mean that the Declaration has no relevance whatsoever when it comes to legal decision making.
Because the Declaration sets forth the bases of our nation’s founding, it is useful for grasping the understanding and intent of the Founding Fathers behind the provisions of the United States Constitution. As the Supreme Court itself put it at the beginning of the last century , it is safe to read the letter of the Constitution in the spirit of the Declaration.
The Declaration refers to the laws of “nature’s God,” declares that human beings are endowed by their “Creator” with the “unalienable” rights to “Life, Liberty, and the Pursuit of happiness,” and concludes with “a firm reliance on the protection of Divine Providence.”  While this language hardly shows a desire to found the nation on Christianity or any other religion or denomination, it does reflect belief in a God that superintends nature, endows people with inalienable rights, and intervenes in human events.
The Founders were asking God for assistance in their endeavor to bring about the political event of separation from Great Britain. So it cannot be accurate to say that the Founders would look with disdain upon the effect of religion upon the actions of individuals acting as citizens. While it is true that the United States was not founded in a belief in Christianity, it is equally true that it was founded in a belief in God.
The attitude of the Founders toward religion is best exemplified by George Washington, who said this in his Farewell Address :
“Of all the dispositions and habits which lead to political prosperity, religion and morality are indispensable supports. In vain would that man claim the tribute of patriotism, who should labor to subvert these great pillars of human happiness, these firmest props of the duties of men and citizens. The mere politician, equally with the pious man, ought to respect and to cherish them. A volume could not trace all their connections with private and public felicity. Let it simply be asked: Where is the security for property, for reputation, for life, if the sense of religious obligation desert the oaths which are the instruments of investigation in courts of justice? And let us with caution indulge the supposition that morality can be maintained without religion. Whatever may be conceded to the influence of refined education on minds of peculiar structure, reason and experience both forbid us to expect that national morality can prevail in exclusion of religious principle.”
From a purely terrestrial perspective it is plain that, for most of us, religion is a necessary aid to virtue, and that a society, especially a democratic society, cannot endure long without virtue prevailing amongst its population. How long can a society remain if its citizens constantly cheat each other or steal from one another? What good outcome can we expect if legislators pass laws with an eye toward satisfying the selfish interests of those who give them money, contemptuously excluding justice from their considerations? How strong is a society that exalts carnal pleasure above most other aspirations? Would a nation that had policies dismissive of the needs of the poor, the sick, or the elderly ennoble humanity, or debase it?
As Washington pointed out, it is possible for some with particularly refined temperaments to be virtuous without the aid of religion. But those who choose no religion, or believe in no God, must be brutally honest and ask themselves this question: when was the last time I resisted a strong temptation?
While there certainly are religious people who seem not to bother resisting temptation, it must be asked what those same people would be like if they saw no need to do so; and Washington clearly was advocating the sincere practice of religion, rather than the modern version without moral requirements. That said, Washington was not suggesting that religion will instill perfection in its adherents, only restraint.
Under the First Amendment, everyone has the right to practice whatever religion they want to, or no religion at all. Given the importance of religion to the maintenance of our society, however, it is fair to point out that those who would restrict the influence of religion to areas of no political importance are hoping for a state of affairs that will hurt the nation rather than help it.