Montana’s clause is one of 37 “Blaine Amendments” passed by states in the late 19th century. They are named for James Blaine, a former Speaker of the House (1869-1875), Senator (1876-1881) and Secretary of State (1889-1892) from Maine who pushed an amendment to the U.S. Constitution barring funding of “sectarian” causes and organizations.
At that time, opponents of the law say, Blaine’s effort mainly targeted Catholic schools and institutions. His amendment failed at the federal level but many states including Montana inserted similar language in their constitutions.
Just like prohibition, Maine was on the forefront of being a nanny state, except it was conservatives pushing it. By 1919 Maine became the deciding progressive vote for women’s suffrage again spearheaded by conservatives.
Don’t forget Maine’s experiment with Prohibition long before it went national.