Lossky's main theological concern was exegesis of mystical theology in Christian traditions. He argued in The Mystical Theology of the Eastern Church that theologians of the Orthodox tradition maintained the mystical dimension of theology in a more integrated way than those of the Catholic and Reformed traditions after the East–West Schism because the latter misunderstood such Greek terms as ousia, hypostasis, theosis, and theoria. In illustration of his argument he cites the collection known as the Philokalia and John Climacus's , as well as works by Pseudo-Dionysius the Areopagite, Gregory of Nyssa, Basil of Caesarea, Gregory Nazianzen, and Gregory Palamas. Georges Florovsky termed Lossky's Mystical Theology of the Eastern Church a "neopatristic synthesis". The genius of Eastern mystical theology lay, he contended, in its apophatic character, which he defined as the understanding that God is radically unknowable in human, thus philosophical, terms. Consequently, God's special revelation in Scripture must be preserved in all of its integrity by means of the distinction between the ineffable divine essence and the inaccessible nature of the Holy Trinity, on the one hand, and the positive revelation of the Trinitarian energies, on the other. "When we speak of the Trinity in itself," said Lossky, "we are confessing, in our poor and always defective human language, the mode of existence of the Father, Son, and Holy Spirit, one sole God who cannot but be Trinity, because He is the living God of Revelation, Who, though unknowable, has made Himself known, through the incarnation of the Son, to all who have received the Holy Spirit, Who proceeds from the Father and is sent into the world in the name of the incarnate Son." The Trinitarian processions in revelation thus produce the energies which human beings experience as grace and by which they are sanctified or "deified". In his Mystical Theology he argued that the theologians of the undivided Church understood that theosis was above knowledge. This was further clarified in his work, Vision of God. In both works Lossky also stresses the differences between Christian thinkers such as Pseudo-Dionysius and such thinkers as Plotinus and the Neoplatonists, asserting that Christianity and Neoplatonism, though they share common culture and concepts, have very different understandings of God and ontology. Vladimir Lossky, like his close friend Georges Florovsky, was opposed to the sophiological theories of Sergei Bulgakov and Vladimir Soloviev. In the words of Nicholas Lossky, "One characteristic of his theology that should be underscored, is that he was not, and always refused to be, a direct descendant of the famous Russian 'religious philosophy'." The term Russian religious philosophy had its origin in the works of the slavophile movement and its core concept of sobornost, which was later used and developed by Vladimir Soloviev.
Eastern theological definitions
Lossky also expressed in The Mystical Theology of the Eastern Church that the Trinity is a doctrine with its technical terms rooted in Hebrew hermeneutics, Greek Platonic and Neoplatonic philosophy as well. The triune God being of one essence or being, which is reflective of mankind hypostatically, inside out. God and experience coming into the person from the external world and into the soul by the influence of the Holy Spirit. The freewill of man functioning as a means to choose good or evil and or choose God or reject God. Hypostasis meaning existence of God. Ousia as essence or being, is the aspect of God that is completely incomprehensible to mankind and human perception, since it is beyond created or is uncreated. The essence of God, being in the Father and then given to the Son and the Holy Spirit both as the hands of God. Ousia as essence or being, defined as "all that subsists by itself and which has not its being in another."
The concept of the Triune God being a single God in essence or Ousia. A single God who as Father or infinite origin is an existence, as Son or flesh is an existence and as Spirit is an existence. One God in one Father.
The Father of the Trinity is uncreated hyper-being in essence or ousia as such is the truly infinite, :wikt:primordial|primordial or original, uncreated origin, the reality of which all things and beings originate from, as the Father Hypostasis. The Father hypostasis in using the term God is used primarily as the name for God. As the term God is interchangeable with the term Father. As Jesus Christ is the Son of God, Son of the Father and the Holy Spirit is the Spirit of God, the Spirit of the Father.
God the Son
The Son of God or Jesus Christ expressing the logos or perfection as the highest ideal, in the material world and God in the flesh. Christ as well, representing mankind, which he inherited from the Theotokos. Christ manifest as generated and or begotten in essence uncreated, by and from God the Father as another reality, Hypostasis of God.
God the Holy Spirit
The Holy Spirit himself being light, life, animation and the source of the uncreated lightphotomos, enlightenment and/or illumination, who proceeds or is manifest by procession from God the Father as another Hypostasis of God. The Holy Spirit and the Christ being the hands of God the Father, reaching in from the infinite into the finite.
Created being
All things that are not God are created beings or are created in their essence. Mankind possesses free will in his finite nature, mankind exists in an indeterminate world. Things as such in their subsistence, are dependent upon something other than themselves. As such divine beings are created beings the origin of their being is ex nihilo. All things that are not God, are created in essence or being. God as hyper-being, and or in essence uncreated can be, by way of his existences, the infinite while generating himself as a man and also be the spirit, that by procession, animates life.
Energies of God
All three hypostasis sharing a common essence or ousia or being, which is referred to as God. The ousia of God being completely unknowable or incomprehensible to mankind since it is uncreated where as nothingness as well as mankind are created. The energies of God the Father having the same hyper-being in that they are without cause and or uncreated. God's energies as uncreated and indestructible. God the Father in his being is not self generated, nor generated from any other, hence the incomprehensibility of God. The Trinity having existences that are comprehensible, but a being that is not created and beyond all things therefore God's hyper-being is incomprehensible. Lossky points out that God's existences can be spoken of but not his being. If one then speaks of God's essence or being as anything outside of incomprehensible, one speaks in direct contradiction to the theoria of Christianity and as such are not true theologians and are instead speaking of God through speculations, rather than experience.
Mysticism and theology
For Lossky, Christian mysticism and dogmatic theology were one and the same. According to Lossky mysticism is Orthodox dogma par excellence. The Christian life of prayer and worship is the foundation for dogmatic theology, and the dogma of the church help Christians in their struggle for sanctification and deification. Without dogmafuture generations lose the specific orthodoxy and orthopraxis of the Eastern Orthodox path to salvation.
