Was America founded to be secular?

The original colonies were established for both economic and religious reasons, but in all cases, religion provided a strong rationale for colonizing. They were not founded to be secular.
The most striking examples of this were the Massachusetts Bay Colony and Pennsylvania. The Massachusetts Bay Colony was founded by Puritan religious dissenters from England who sought a religious freedom not available in their home country. They came to America to avoid being persecuted for not attending worship, paying tithes, or adhering to the precepts of the Church of England, the official religion of the English. Their explicit desire was to establish a city on a hill, a light to guide the world, by creating a Puritan Christian theocracy in the New World. They had their own ideas of how Christianity should be practiced and did not tolerate dissent, for example, executing Quaker Mary Dyer when she would not stop preaching Quakerism in the colony.
Pennsylvania was also started for religious reasons: Penn, a prominent Quaker, wanted a place of refuge for persecuted Quakers. However, his ideals in creating his colony were somewhat different from those of the Puritans: he believed in religious freedom and opened his colony to all sorts of persecuted religious groups, such as German anabaptists.
Three other New England colonies: Rhode Island, New Hampshire, and Connecticut, were founded in reaction or rebellion against the religious orthodoxy of the Massachusetts Bay Colony. Even colonies not founded on explicitly religious grounds, such as Virginia, still had as an important goal the conversion of Native Americans to Christianity, and the vision of themselves as Christian states, even if they tolerated non-Christian faiths.