And if Athanasius were around today, he would (or would he)probably declare that all of the separate Catholic rites (not the right word, but I’m referring to Eastern Orthodox, Greek Orthodox; Russian Orthodox; Armenian; & etc as heresies, as he did those who followed Arius and other small Christian sects/groups in the 3rd & 4th Centuries.
And then we have the seeking for “one” church to be the official church of the renewed Roman Empire under Constantine and finally Theodosius.
But bottomline for me is all Christians are saved by the Grace of Salvation through Jesus, who was sent here by His Father to rescue us/our souls from perishing on this spec of galactic debris.
I’m glad you mentioned Theodosius.
The Roman Emperor Theodosius established the Roman Catholic Church in 380 AD and set about eliminating every other branch of Christianity.