Catholicism did not conquer. Paganism worked its way into the apostate churches and set up it's throne there, becoming, eventually, the Papacy.
Rev 13:2 And the beast which I saw was like unto a leopard, and his feet were as the feet of a bear, and his mouth as the mouth of a lion: and the dragon gave him his power, and his seat, and great authority.
The only problem with that idea is the Roman pagans killed all the popes for the first 300 years, starting with Peter.
Why the Romans martyred them, because they wouldn’t apostatise.
Only Catholics died in the Roman persecutions in the Arenas. In fact all pagan Europe was conquered by Catholicism.
Protestantism had a completely depaganised Europe and British Iles before they existed, and it was all because Catholics brought them all to Christ.
It was Catholics that preserved the scriptures through so many horrific persecutions and martyrdoms.
It was Catholics that first determined and assembled the Canon of the Bible itself.
Where were protestants and Baptists in these times. Nowhere. What did they have to do with the preservation of the Scriptures and determining of the Bible. Nothing.
The easy believers showed up after the greatest work was done. Interpret scripture for yourself, the truth of them be damned.
Subjective Opinion is the whole of the Law according to them.
Man made churches appeared, forging their doctrines on subjective changeable human interpretations of Scripture hammer and tongs.
All traditions of men burning incense to their opinions.
“ Without the Catholic Church, we would have no Bible “ Professor Peter Flint, Baptist translator of the Dead Sea Scrolls.
“[N]or does it consist in this, that he should again falsely imagine, as being above this [fancied being], a Pleroma at one time supposed to contain thirty, and at another time an innumerable tribe of Aeons, as these teachers who are destitute of truly divine wisdom maintain; while the Catholic Church possesses one and the same faith throughout the whole world, as we have already said.” Irenaeus, Against Heresies, 1:10,3 (A.D. 180).
“Concerning this Holy Catholic Church Paul writes to Timothy, ‘That thou mayest know haw thou oughtest to behave thyself in the House of God, which is the Church of the Living God, the pillar and ground of the truth’” Cyril of Jerusalem, Catechetical Lectures,18:25(A.D. 350).
“And if ever thou art sojourning in cities, inquire not simply where the Lord’s House is (for the other sects of the profane also attempt to call their own dens houses of the Lord), nor merely where the Church is, but where is the Catholic Church. For this is the peculiar name of this Holy Church, the mother of us all, which is the spouse of our Lord Jesus Christ, the Only-begotten Son of God.” Cyril of Jerusalem, Catechetical Lectures, 18:23,26 (A.D. 350).