To understand the Trinity, an entirely new way of thinking about reality had to be developed. The old philosophical framework, the old paradigm, nor the old lens, had the terminology, parameters or scope for dealing with what scripture revealed about the three-ness, yet one-ness of God. Understanding the nature of the orienting dynamic for reality (God) had to be re-approached. So the Church, under the inspiration of the Holy Spirit, began to rebuild the paradigm for understanding God (and therefore true reality). As a result, the philosophical framework for thinking about reality underwent a shift. The paradigm was rebuilt and the lens became sharper with the development of Trinitarian thought.
Because a shift in theology brings with it an inevitable shift in philosophical commitments, it becomes critical that Trinitarian thought and its philosophical undergirding becomes the framework for all theologizing. That is, all theologizing must be done out the philosophical foundations of Trinitarian thinking. Unfortunately, this has not always been the case, especially when it comes to soteriology. In the past, and even now, there has been a tendency in orthodox Christian circles to maintain a soteriology within a philosophical framework that is at odds with the philosophical foundations of Trinitarian thought. The emphasis of salvation often times becomes justification and glorification while sanctification is left behind as the remnant.
While justification and glorification are undoubtedly critical components of a biblical soteriology, they are not the entire story. The neglect of sanctification, it seems, is the result of building a soteriology within a philosophical framework that is at odds with Trinitarian thought. At the very least, a soteriology whose emphasis is justification and glorification certainly neglect the foundations of Trinitarian thought. It is critical that soteriology be approached through the Trinitarian lens and all of its philosophical foundations. Approaching soteriology with the philosophical foundations of Trinitarian thought brings sanctification to the forefront of salvation.
So, how exactly did the encounter with the Trinity effect previous philosophical foundations for a biblical worldview? The reality of the Trinity changed the way orthodox theologians and Christian philosophers thought about being (ontology) and personhood. Because the Trinity posed a new way of thinking about the very nature of God (who is the I Am), the way to think about being demanded a change. Christian philosophers and theologians revisited the questions, “What determines identity? What is it to be?” Because the Church was in a position for ontological reconsideration, it leaned into (and built upon) the Roman philosophical concept of personhood as the key for understanding ontology. John Zizioulas writes, “The concept of the person with its absolute and ontological content was born historically from the endeavor of the Church to give ontological expression to its faith in the Triune God” (Zizioulas, Being as Communion, 1997).
For thousands of years, humanity understood ontology to be something quite unified. Namely, Greek philosophy understood human ontology to be centered in the unity of the cosmos. John Zizioulas calls this “ontological monism” (Zizioulas, 1997). He writes:
Ancient Greek thought remained tied to the basic principle which it had set itself, the principle that being constitutes in the final analysis a unity in spite of the multiplicity of existent things because concrete existent things finally trace their being back to their necessary relationship and “kinship” with the ‘one’ being, and because consequently every ‘differentiation’ or ‘accidence’ must be somehow regarded as a tendency towards “non-being”, a deterioration of or “fall” from being (Zizioulas, 1997).
Trinitarian thought challenged this ontological paradigm and again, it was the Roman concept of personhood that became the means for grasping a new understanding of identity and being. With the development of Rome and Roman states through the expansion of the Romans Empire, there emerged the concept of identity being determined by one’s relationship with society and its members as well as the state. Ontology became to be understood as something inseparable from communion. One’s relationship with others and society determined identity. Without an economic and legal connection to society, one had no identity. Ontology is attributed through personhood, and personhood is attributed through communion. A person’s being and freedom is determined through his/her relationships.
This ontological approach provided the philosophical framework for thinking about the Trinity as one God, who is three Persons. Each member of the Trinity, as a Person, has an identity that is distinct from the other two Persons, however, that identity (ontology) is determined and attributed via the individual’s membership within the communion. So, the deity of each member of the Trinity is inseparable from the personhood of each. None of the members of the Holy Trinity can forfeit personhood without forfeiting their diving being. The Son, for example, can only be divine and a person. His divinity is determined through his personhood, which is attributed through his communion with the Father and Holy Sprit.
Understanding ontology as being attributed through communion has a tremendously profound impact on soteriology. If the essence of salvation according to scripture is reconciliation and a rejoining with the three Persons of the Holy Trinity, then there is an ontological demand on humanity that comes with assimilation into the Triune communion. That demand is sanctification. That is, to be in communion with another person naturally results in an ontological shift. The engagement of another in communion determines one’s being. Because communion determines being, there is a reciprocal effect of ontological union. Humanity is incapableof being in fellowship with the Holy Trinity a part from actually becoming holy. The Holy Trinity would compromise its nature to be joined in communion with one that is immoral. Because the nature of the Trinity cannot be compromised, then sanctification is an absolute in order for humanity to be reconciled to God. Any soteriology that allows sanctification to take a back seat to justification and glorification is one that has considered the state of humanity and its hope with a non-Trinitarian lens.
So, Trinitarian thought is in great harmony with Hebrews 12:14, “Strive for peace with everyone, and for the holiness without which no one will see the Lord”. Paul, in Romans, is clear that justification never comes without sanctification (Romans 6:1-14). The death and resurrection of Christ offers much more than forgiveness. Christ offers forgiveness so that we can reunite with him and therefore undergo an ontological change. The cross is the only means by which people can join in fellowship with the Holy Trinity because of its power to create a means for ontological change. This is why Christ is the only way of salvation. As orthodox Christians, to maintain that God is One, yet Three, we must also maintain that sanctification is at the center of Christ’s redemptive work in actually making those that love him righteous.
 I believe that this is why Jesus’ teaching was so radical. He was able to think about salvation in terms that no other teacher had. He understood reality in light of the three-ness of God but his opponents theologized within an incomplete philosophical framework.
 Interesting to note here is that this idea is paralleled in the ancient Near East in the patriarchal paradigm. In patriarchal culture, one’s identity is determined by one’s familial relationships, namely, one’s relationship to the patriarch. In other words, this concept is not entirely unique to early Roman thought.
 In fact, being as communion greatly impacts all theologizing, not just soteriology.