21. [excerpted] Justice therefore forbids, and reason itself forbids, the
State to be godless; or to adopt a line of action which would end in
godlessness - namely, to treat the various religions (as they call
them) alike, and to bestow upon them promiscuously equal rights and
privileges.
Pope Leo XIII, Libertas (1888)
LIBERTAS (On the Nature of Human Liberty)
http://www.ewtn.com/library/encyc/l13liber.htm