When Christ says He is the truth and at the same time the life of the world, He introduces into truth a content carrying ontological implications. If the truth saves the world it is because it is life. The christological mystery, as declared by the Chalcedonian definition, signifies that salvation as truth and life is possible only in and through a person who is ontologically true, i.e. something which creation cannot offer, as we have seen. The only way for a true person to exist is for being and communion to coincide. The triune God offers Himself the only possibility for such an identification of being with communion; He is the revelation of true personhood.
John D. Zizioulas. Being and Communion. Studies in Personhood and the Church, London, DLT, 1985 (2004), 107.
In order for Christ to be Saviour, He needs to not only be God but also to be a true person. Our individualized human experience cannot provide us with an example of what it means to be fully and ontologically personal, for our being is determined by creaturehood. While we can understand the cross by way of analogy (someone who loved us so much as to die for us),
without an ability to follow it into the resurrection (a person who conquered death) Christology brings with it nothing ontological. Christ is truth precisely because in Himself He shows not just being, but the persistence, the survival of being, through the resurrection Christology shows that created existence can be so true that not even human freedom can suppress it, as was actually attempted on the cross. Truth and being are existentially identified only in Christ’s resurrection, where freedom is no longer fallen, i.e. no longer a threat to being. (108)
This means that truth is moved from the realm of the individual to that of the person. In Christ, the division of “natures” is changed into an otherness through communion.
This shift of Christology away from our individualized existence seems to many to lead to a picture of a Christ who is not “human”; nevertheless, what we have just said shows that unless in Christology this “de-individualization” of Christ takes place, its existential implications will no longer have ontological importance. (109)
Zizioulas claims that attempts to individualize Christ create insurmountable problems for Christology. They may provide ethically or psychologically orientated soteriologies, or result in substitutional theories, but remain ontologically irrelevant, for they cannot explain how humanity and creation are existentially connected with this individual.
This leads to the relationship between Christology and pneumatology that Zizioulas discusses in the following section.