Tolkien converted to Catholicism along with his mother, at a young age. (If memory serves, he was 8). As a result of her conversion, Tolkien's mother, who was a widow, was ostracized by most of her relatives and lived under difficult circumstances. She died when Tolkien was still a boy, and he was raised by his guardian, a priest.
Tolkien regarded his mother as a martyr for the Faith, since her ill health was brought on by the ostracism of her Protestant relatives.