All Christians were Catholics (I am including Orthodox with the Catholics because they the same sacraments), before protestants came along over 1,500 years after Christ died. The Catholic Church canonized the New Testament and the OLD TESTAMENT. The Catholic Church determined what books were divinely inspired and what books were not. The same Bible that protestants claim Catholics don’t know was compiled by Catholics. It is a Catholic document. Without the Catholic Church it wouldn’t exist. Sacred tradition goes hand in hand with scripture. Only protestants have a hard time figuring that out.
There was nothing to protest until Constantine founded the catholic apostasy in the 4th century, so the followers of Yeshua’s Way were not called “protestant” at first.
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No, the catholic church did NOT canonize the Old Testament.
Jesus and the apostles referred to the Old Testament as the Word of God and as authoritative BEFORE the catholic church canonized anything.
Old Testament saints like David, Daniel, Isaiah, etc.part of the invisible church long before Peter, Paul, James and John much less Pope Leo.