There is no god in which we all trust

That diabolical Hell conceived principle of persecution rages among some and to their eternal Infamy the Clergy can furnish their Quota of Imps for such business.

James Madison in another letter to William Bradford, April 1, 1774:

Religious bondage shackles and debilitates the mind and unfits it for every noble enterprize, every expanded prospect.

George Washington led the revolutionary armies, presided over the Constitutional Convention and was the first president.

The only religious reference in the original Constitution follows:

Article VI

... no religious Test shall ever be required as a Qualification to any Office or public Trust under the United States.

On March 4, 1789, the new government under the Constitution began operating. James Madison introduced the Bill of Rights to the First United States Congress in the same year, and they came into effect on December 15, 1791. The First Amendment contains the only other mention of religion.

Amendment 1

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.

Former Supreme Court Justice O’Connor commented on this amendment:

In my opinion, the First Amendment is the single most important part of the Constitution. It protects some of the most basic human rights and reflects a view of the dangerous places government might tread.
...
Some of the first colonists of the nation for which the Constitution was written had been seeking to escape religious persecution. The constitutions of several of the states prohibited public support of religion (though some did explicitly support or demand adherence to Christianity). Above all, the many varying sects of Christianity in America required that to be fair to all, there could be preference to none. It would have been disgraceful for anyone to wish to leave the United States because of religious persecution. So the authors decided it best to keep the government out of religion. This is not to say that the United States was not or is not a religious nation. Religion plays a big role in the everyday life of Americans, then and now. But what the authors were striving for is tolerance ... something I fear contemporary Americans are lacking.
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George Washington was not a Christian. He was, like many men of the Enlightenment, a Deist. Deists believed in God as a Creator who rules the world by rational laws, and that humans are rational beings, capable of guiding their lives by the light of reason. Deists rejected the claims of supernatural revelation and took no share in formal religious practices. Washington attended church with his wife but refused to take communion.

Washington had a vision of the United States as a diverse polity. Three minorities in the new nation were the Irish Catholics, the Jews and the blacks. Washington expressed his vision of multiculturalism in an address to the Members of the Volunteer Association of Ireland, December 2, 1783: