I once again point out this utterly utilitarian justification of religious belief.
The religious beliefs of the settlers and founders of the United States is an interesting historical fact (just as is the religious beliefs of the founders of all other countries), but it has nothing to do with what is the One True Religion.
Every single human being has the obligation to seek out, acknowledge, and obey the One True G-d. One does not do this by merely adhering to the religion of the founders of one's country (else there would be a different "one true religion" for every nation on earth!).
George Washington was a great man, but he did not create the universe. Seek out the True G-d, and you can't do that by merely seeking to share George Washington's religious beliefs.
Of the thirteen original colonies, only two - Massachusetts and Rhode Island - had any religious component to their founding.
The other eleven were founded for commercial and political reasons.
Of the two with a religious component one - Rhode Island - was founded by settlers fleeing from the religious persecution visited upon them by the settlers of the Massachusetts colonies.
And the persecutors who ran the Massachusetts colonies were actually a minority of the colonists - they had the land patents, but most of the settlers were recruited from a variety of Englishmen seeking their fortunes, not people motivated by a particular sect.
99% of the first generation of permanent American colonists were there for commerce, not theology.
Maybe the writer or the poster believes that the Founders -- whether the Puritans, or the Anglicans, or the Baptists and Methodists or the deists -- did believe in the one true religion. You may not agree but that doesn't necessarily mean that the view represented in the article is utilitarian or ethnocentric.