Could you please explain why you believe there will be many catholics saved in the rapture?
I believe that the 7 letters of Rev. 2-3 were written to actual 1st Century churches, but are also descriptive of different periods in the Church Age. The letter to Ephesus describes the 1st Century, Smyrna the 2nd and 3rd Centuries, and Pergamus is when the Church and the Babylonian system were joined together in the 4th Century. Those Churches no longer exist in the world.
The remaining four churches all sprang from the Pergamus union and all are still in the world today. Thyatira represents the Catholic Church, Sardis the main line protestant denominations, Philadelphia the evangelicals and Laodicea the end tines apostate Church.
Thyatira and Sardis are both described as having some who are saved and some who are not. Philadelphia is the Church of the Rapture where everyone is saved, and Laodicea is the post-rapture church where no one is.
This is one reason why I believe there will be some saved out of the Catholic Church and some out of liberal protestantism. I believe the same can be said of Mormons, even though Mormonism is not mentioned in the Bible.
(On the flip side of that coin, I think there’ll also be many people from Bible believing churches, where you’d expect everyone to be saved, who will be left behind.)
My other reason is that it’s not what it says over the door of the church you attend that matters, it’s Who you have in your heart. Everyone who has fulfilled the minimum standard for salvation, believing in our heart that Jesus died for all of our sins, will be saved irrespective of any other circumstance. (Matt. 7:7-8 & Romans 10:13)