>>17800415
Catholics and Orthobros split over a host of things, one of the main issues being the filioque.

all Apostolic and Magisterial Churches conform to the Nicene Creed, declared at the first council of Nicaea.
Its about as important as the doctrine of the resurrection, if you don't believe in the creed, you're not a Christian.

Problem was, the Roman church attempted to change the creed in the 6th century. Originally, when the Creed mentions the Holy Spirit it read:
>I believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father.
>who with the Father and the Son is adored and glorified,
>who has spoken through the prophets.

However, the Romans changed to creed to NOW read:
>I believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father AND THE SON.
>who with the Father and the Son is adored and glorified,
>who has spoken through the prophets.

The term "and the Son" is read in Latin as "filioque" hence the name of the controversy.

This sparked a lot of controversy, not only for the change itself, but the theological implications.
Orthobros believed that it was undermining the Holy Spirit to precede both the Father and Son and disrupted the balance of the trinity.
Catholics believe the Son precedes and can send the Holy Spirit.

There were a number of other reasons for the Schism, but this one was the straw that broke the camel's back for the East.
There have been a number compromises put forth to try and reunite the Church from both sides. The main one being to change the creed from "AND the Son" to "THROUGH the Son" which would fix the Orthobros theological issues, but they're literally Orthodox. They hate change. Its in the name.