The New Testament does not use the actual noun kén?sis but the verb form kenó? occurs five times (Ro.4:14, 1Co.1:17, 9:15, 2Co.9:3, Phil.2:7). Of these five times it is Phil 2:7, in which Jesus is said to have "emptied himself", which is the starting point of Christian ideas of kenosis.
The kenotic ethic is based on Philippians 2:7, where Jesus is described as having "emptied himself...". Proponents of a Kenotic ethic take this passage not primarily as Paul putting forth a theory about God in this passage, but as using God's humility exhibited in the incarnation as a call for Christians to be similarly subservient to others.
Orthodox theology emphasises following the example of Christ. Kenosis is only possible through humility and presupposes that one seeks union with God. The Poustinia tradition of the Russian Orthodox Church is one major expression of this search.
Kenosis is not only a Christological issue in Orthodox theology, it has moreover to do with Pneumatology, namely to do with the Holy Spirit. Kenosis, relative to the human nature, denotes the continual epiklesis and self-denial of one's own human will and desire. With regard to Christ, there is a kenosis of the Son of God, a condescension and self-sacrifice for the redemption and salvation of all humanity. Humanity can also participate in God's saving work through theosis; becoming holy by grace.
Therefore, in Eastern Orthodoxy, theosis never concerns becoming like God in essence or being, which is pantheism; instead, it concerns becoming united to God by grace, through his Energies. Orthodox theology distinguishes between divine Essence and Energies. Kenosis therefore is a paradox and a mystery since "emptying oneself" in fact fills the person with divine grace and results in union with God. Kenosis in Orthodox theology is the transcending or detaching of oneself from the world or the passions, it is a component of dispassionation. Much of the earliest debates between the Arian and Orthodox Christians were over kenosis. The need for clarification about the human and divine nature of the Christ (see the hypostatic union) were fought over the meaning and example that Christ set, as an example of kenosis or ekkenosis.
There is another enemy of the faith of Chalcedon, widely diffused outside the fold of the Catholic religion. This is an opinion for which a rashly and falsely understood sentence of St. Paul's Epistle to the Philippians (ii, 7), supplies a basis and a shape. This is called the kenotic doctrine, and according to it, they imagine that the divinity was taken away from the Word in Christ. It is a wicked invention, equally to be condemned with the Docetism opposed to it. It reduces the whole mystery of the Incarnation and Redemption to empty the bloodless imaginations. 'With the entire and perfect nature of man'--thus grandly St. Leo the Great--'He Who was true God was born, complete in his own nature, complete in ours' (Ep. xxviii, 3. PL. Liv, 763. Cf. Serm. xxiii, 2. PL. lvi, 201).
In John of the Cross's thinking, kenosis is the concept of the 'self-emptying' of one's own will and becoming entirely receptive to God and the divine will. It is used both as an explanation of the Incarnation, and an indication of the nature of God's activity and will. Mystical theologian John of the Cross' work "Dark Night of the Soul" is a particularly lucid explanation of God's process of transforming the believer into the icon or "likeness of Christ".
Since some forms of Unitarianism do not accept the personal pre-existence of Christ their interpretations of Phil. 2:7, and the concept of "kenosis", Christ "emptying" himself, take as a starting point that his "emptying" occurred in life, and not before birth. However, as Thomas Belsham put it, there are varying views on when in life this emptying occurred. Belsham took this to be at the crucifixion, whereas Joseph Priestley took this to be in the Garden of Gethsemane when Christ did not resist arrest. The Christadelphian Tom Barling considered that the "emptying" of Christ was a continual process which started in the earliest references to Christ's character, Luke 2:40,52, and continued through the temptations of Christ and his ministry.
The equivalent to ken?sis in Gnostic literature is Christ's withdrawal of his own luminosity into himself, so as to cease dazzling his own disciples. At the request of his disciples, "Jesus drew to himself the glory of his light".