This statement in the Declaration of Independence is occasionally held up as an indication the founding fathers of the United States intended the country to be Christian. It’s important to point out the Declaration of Independence is simply a group letter to a man who believed he was anointed by god to be king. It was nothing more than a breakup letter.

The founders knew the king believed his might was right and ordained by god, so they acknowledged a creator. They also acknowledged that creator gave all men the right to self and by extension, the right of free will. But the Declaration of Independence is not a governing document. It has no relevance beyond it’s purpose of severing the tie between the empire and the colony’s. 

But what did the founders actually think of this idea? Is America supposed to be secular or nonsecular?

First, we have the federalist papers where the founders put their thoughts and extensions of the ideas in the constitution for posterity. Without reading the federalist papers, we can see the words, but much of the intent is missing. (Source below)

Second, we have many quotes from many founders and leaders over the course of our nation. (Source below)

A select few:

All persons shall have full and free liberty of religious opinion; nor shall any be compelled to frequent or maintain any religious institution.

Thomas Jefferson

The [president] has no particle of spiritual jurisdiction…

Alexander Hamilton

The United States of America have exhibited, perhaps, the first example of governments erected on the simple principles of nature…. [In] the formation of the American governments … it will never be pretended that any persons employed in that service had interviews with the gods, or were in any degree under the influence of heaven… These governments were contrived merely by the use of reason and the senses.

John Adams

The divorce between Church and State ought to be absolute. It ought to be so absolute that no Church property anywhere, in any state or in the nation, should be exempt from equal taxation; for if you exempt the property of any church organization, to that extent you impose a tax upon the whole community.

James A. Garfield

Further, in the Treaty of Tripoli, John Adams wrote and signed, the US Senate and George Washington approved;

As the Government of the United States of America is not, in any sense, founded on the Christian religion,—as it has in itself no character of enmity against the laws, religion, or tranquility, of Mussulmen [Muslims],—and as the said States never entered into any war or act of hostility against any Mahometan [Mohammedan] nation, it is declared by the parties that no pretext arising from religious opinions shall ever produce an interruption of the harmony existing between the two countries.

It’s abundantly clear the founders did not want religion to influence governance. They looked across history and saw with a clear eye what we know is true today.

That is, in all of human history, more people have died due to one religion persecuting another, and more wars have been fought in the name of one or more gods, than due to any other cause. 

Christianity is no exception. The crusades was Christianity’s attempted elimination of Islam.

Federalist Papers: https://guides.loc.gov/federalist-papers/full-text#TheFederalistPapers-1

Quotes on separation of church and state: https://www.azquotes.com/quotes/topics/separation-of-church-and-state.html