Margaret Wise Brown's mother was Episcopalian and her father was Presbyterian, but both parents were apparently lapsed in their faith. Although brought up in a vaguely Protestant home and exposed to a devoutly religious grandmother (a Protesant), Margaret Wise Brown appears to have grown up without a strong religious identity and was not known to have been a regular churchgoer.
Margaret Naylor Wise Johnson was the only grandparent that author Margaret Wise Brown ever met. "Grandma Naylor" was a "pious woman whose conversation was laced with quotations from Scripture." When she visited, the children were sent to Sunday school, which neither Maude (an Episcopalian) nor Robert (Presbyterian) otherwise encouraged them to attend." [Source: Leonard S. Marcus, Margaret Wise Brown: Awakened by the Moon, Beacon Press: Boston, Massachusetts (1992), page 10.]