Luke 10:21 In that hour Jesus rejoiced in spirit, and said, I thank thee, O Father, Lord of heaven and earth, that thou hast hid these things from the wise and prudent, and hast revealed them unto babes: even so, Father; for so it seemed good in thy sight.
As Spurgeon declared Calvinism IS the Gospel, therefore God will never allow it to become redundant.
As for the historic Roman Catholic "umbrella," there were two kinds of people under that umbrella prior to the God ordained Reformation. One group was Christian, the others were Roman Catholics. As you know from experience the Roman Catholics were idolatrous heretics who introduced blasphemy into their worship, who introduced the evil traditions into church to the detriment of Biblical doctrines. Thus this part of the umbrella was the false church set up by Satan and, as today, was/is run by the papal antichrist.
The God ordained Reformation removed the Christian element from the idolatrous Roman Catholic umbrella, they then protested all the false heretical unBiblical practices and became the Protestant Church, which is the Church which sticks to the Bible and the truth.
What is left today, the Roman Catholic group, remains ignorant of the truth and is just as false and idolatrous as ever. These are unsaved reprobates doing a works based religion going no where.
Saved Christians have always left the Roman Catholic conglomerate spiritually and now today physically. Halleluiah.