What does the percentage of the population who are Christian have to do with anything? The early settlers were here as part of a business enterprise. Religion was a secondary and a later reason for colony development.
"England made its first successful efforts at the start of the 17th century. Most of the new English colonies established in North America and the West Indies, whether successful or otherwise, were proprietary colonies. Proprietors were appointed to found and govern settlements under mercantile charters granted to joint stock companies. Soon, there was a rapid increase of English colonial activity, driven by the pursuit of new land, trade, and religious freedom.
The Thirteen Colonies were the colonies on the Atlantic coast of North America, starting with Virginia in 1607, and ending with Georgia in 1733. The colonies were Delaware, Pennsylvania, New Jersey, Georgia, Connecticut, Massachusetts Bay, Maryland, South Carolina, New Hampshire, Virginia, New York, North Carolina, and Rhode Island and Providence Plantations. Each colony developed its own system of self-government."
https://courses.lumenlearning.com/boundless-ushistory/chapter/the-british-empire-in-north-america/#:~:text=The Plymouth Company was given,settlements at Jamestown in 1607.