Every Sunday we confess in the Creed that we believe in “one, holy, catholic, and apostolic Church”. But what do we mean when we confess the Church as catholic? For many people the word “catholic” simply means “Roman Catholic”—i.e. the Christian confession centering upon the universal leadership of the Pope of Rome. Obviously reading such usage into the Creed would be anachronistic, for the Church of the fourth century did not center around the leadership of the Bishop of Rome in the same way as churches in the West would much later when the term “Roman Catholic” became current.
The term “catholic” comes from the two Greek word κατα ολος/ kata olos meaning “according to the whole”, so that whatever is catholic is therefore whole, full, general, common. It is used in contrast to something that is kata meros, or according to a single portion. The first extant use of the term is by St. Ignatius of Antioch in the early second century where he says, “Wherever Christ Jesus is, there is the catholic church” (from his Letter to the Smyrneans). The Church is catholic in the sense that each local assembly manifests the whole Christ, the fullness of the faith, the entire truth, and all of salvation. The opposite of “catholic” is “partial” and a church which was not catholic would have only a part of the truth of Christ and a portion of His saving power. All religions have a part of the truth, but the Church alone has the whole truth because the Church alone has the whole Christ.
Later on, around the time of St. Augustine, the term “catholic” took on a geographical nuance, and meant something universal in contradistinction to something that was merely local. In this new sense, the Church was catholic because it was universal, and had spread into all the world, compared with the heresies which began in a particular locality and for the most part remained in particular localities. The true Church was catholic and universal; the heresies were limited and local. This is true, but it does not represent the earliest meaning of the word “catholic”. The Church was catholic even when it had not spread beyond the city of Jerusalem, because even before its expansion it possessed the whole Christ and the whole truth.
But it is true that the catholic Church which possesses the whole truth, may be compared to the heresies which spring up in particular locales and which concentrate on particular truths to the detriment of the whole and balanced total picture. Heresies are not so much denials of the truth as they are pathological concentrations on certain aspects and parts of the truth and the substitution of these portions of the truth for the whole truth. Take for example Arianism: it is true that the Father is the unique fountainhead of hypostatic divinity, so that the Son finds His hypostatic source in the Father. Arianism takes this truth and concentrates upon it to the exclusion of other truths, such as the essential equality of the Son with the Father, and so becomes heretical by asserting that the Son is essentially inferior to the Father. Heresy is not the perverse repudiation of received dogma, but a cancerous growth of one part of the dogma to the point where the part swallows up and becomes the whole. Heresies, which always begin as local movements, substitute a partial truth for the whole truth. Heresies specialize in one truth to the exclusion of other truths; the Church is catholic because it integrates all the various truths into one harmonious whole.
Two conclusions follow from the confession of the catholicity of the Church.
First of all, since being catholic means possessing the whole truth we confess that the Church is the natural home of all truth. If something is true, it belongs to the Church. It was from this theological impulse that St. Justin declared that whatever the pagan philosophers uttered that was true was the property of the Church. The Church is not narrowly and possessively denominationlistic, only accepting truths discovered by her own members. It is catholic, and whatever in the world was true was her property as well. The truth uttered by pagan philosophers (such as the Stoics) was Christian truth and the Church claimed it as its own. Today includes this scientific truth. The Church need not feel threatened by the advances of genuine scientific discovery, for all truth belongs to God, and forms part of the Church’s inheritance.
Not all Christians throughout the years were quick to recognize this, as Galileo and his heirs could attest at their cost. But whatever is true is part of the Church’s patrimony nonetheless. The Church retains a generosity of approach to truth, since it worships the God who says, “I am the truth”. Not every truth, insight, or discovery needs to bear an Orthodox label or be authored by an Orthodox Christian. Like St. Justin Martyr, the Church has enough self-confidence and humility to learn from everyone. We do not check the identity card of historians, theologians, and scientists before accepting their conclusions. Our question is not, “Is the scholar or scientist Orthodox?”, but rather, “Is the scholar or scientist saying something that is true?” If the answer is “Yes” then we receive that truth with gratitude as a blessing from the Father of lights from whom comes every good and perfect gift.
Secondly, since being catholic involves universality, we refuse to act apart from the rest of the Church spread out through all the world. Heresies begin when someone hardens his heart and prefers his own opinion to the universal consensus of the Church. Acting as a catholic Christian means respecting the consensus and not acting unilaterally. This admittedly can be very frustrating, because it means that concerted action can be very slow as we wait for a consensus to be built. The Church seems often to move at a glacial pace. But patience is always a virtue, especially in ecclesiastical matters. Striking out on our own in defiance of universal Orthodox consensus—especially if done by patriarchs and bishops— almost always ends in disaster and schism. Being catholic often means not breaking rank for the sake of our own opinions. Heresy and schism are always easy, which of course is why there are so many of them. Patience and preserving catholic unity are hard. All the more reason to confess the catholicity of the Church every time we say the Creed.
Source: https://blogs.ancientfaith.com/nootherfoundation/the-marks-of-the-church-the-church-as-catholic/