Thomas Jefferson explains himself—isn’t it interesting that we never hear about this quote?:
In America, the sisters of the Ursuline convent in New Orleans were thus understandably concerned about a change in governments and about coming under the authority of the United States following the Louisiana Purchase from France in 1803. Fearing how the mostly-Protestant, Anglo-Saxon U.S. would treat Catholic institutions, their superior wrote (link to a copy) President Thomas Jefferson in 1804 expressing concern over their rights and the future of their ministries of providing medical care and of running a convent and girls’ school (which they had done since twelve Ursuline nuns from France first arrived in New Orleans in 1727.)
Jefferson’s response was remarkable.
He assured them that the civil authorities had no intention of interfering in their affairs and that the charitable and educational works of the “holy sisters” would be respected and allowed to continue.
“The principles of the constitution and government of the United States are a guarantee to you that it will be preserved to you, sacred and inviolate, and that your institution will be permitted to govern itself according to its own voluntary rules, without interference from the civil authority,” he wrote.