Most of the fifty-five Founding Fathers who worked on the Constitution were members of orthodox Christian churches and many were even evangelical Christians. The first official act in the First Continental Congress was to open in Christian prayer, which ended in these words: "...the merits of Jesus Christ, Thy Son, our Savior. Amen". Sounds Christian to me.

Ben Franklin, at the Constitutional Convention, said: "...God governs in the affairs of men. And if a sparrow cannot fall to the ground without His notice is it probable that an empire can rise without His aid?"

John Adams stated so eloquently during this period of time that; "The general principles on which the fathers achieved Independence were ... the general principles of Christianity ... I will avow that I then believed, and now believe, that the general principles of Christianity are as etemal and immutable as the existence and attributes of God."

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No doubt many of the Founders of the USA had belief in a God, and most of them Christian.

But you don't have to wonder, guess or seek to explain how they set up the nation; it was set up as a secular state with no established state religion and with a separation of church and state.

You can find all that info in the Founding documents.