Welcome to the forum.
How serious do you take the Great Schism of 1054? What practical difference does it make in your personal life?
I take it with absolute seriousness. The 1054 Schism is not a dusty piece of history, it is the definitive moment the West broke away from the original, unchangeable, apostolic Church to introduce theological innovations like the
Filioque and Papal supremacy. It is therefore no surprise that Protestantism arose as a result of Roman Catholicism. Heresies have a snowball effect, they're compounding. You have to actually look at how the Church operated in the first millennium...which shows that it was conciliar. In the first millennium, Christianity was a Pentarchy of 5 patriarchates: Jerusalem, Antioch, Rome, Constantinople, and Alexandria. Rome broke away from the Pentarchy, and the consensus of the Church.
St. Justin Popovic described Protestantism not as being the opposite of Catholicism, but its loyal child because it has applied the papacy to the individual. Roman Catholics to us are the first Protestants. In fact, they are not even Catholics, they are papists. We are Orthodox Catholics, true Catholics.
By adopting Absolute Divine Simplicity (ADS), scholastic theologians like Thomas Aquinas defined God as an abstract, unapproachable essence with no real internal distinctions. If God is only a distant, unknowable essence, human beings cannot truly interact with anything uncreated. The West had to bridge the gap with created effects (like "created grace"), effectively pushing God's active, living presence out of the physical cosmos. They reduced theology to rationalistic puzzle-solving.
Roman Catholics frequently like to boast about their numbers worldwide to prove that they have catholicity (universality), and we don't. But Catholicity also means fullness of Truth. Scripture says the path is narrow..meaning Truth is not determined by numbers or popularity.
Right now we're dealing with the issue of ecumenism. The RCC and Orthodox Ecumenical Patriarch want to unite..but unity is false if it's not grounded in truth. We have our own corrupt bishops, but the difference is that we don't put all our stock into one person like the RCC does. We put our stock in Christ, the living tradition guided by the Holy Spirit.