IIRC, he was raised Protestant.
Disciples of Christ, then Eureka College then pastor Don Moomaw, a Presbyterian, was his closest religious advisor in CA.
RE Reagan:
His momma was Disciple of Christ, poppa was Irish Catholic.
Evidently, Ronaldus Magnus was baptized into the DoC faith, at least according to Wikpedia.
https://en.wikipedia.org/wiki/Ronald_Reagan