Vladimir Lossky writes:
Far from being mutually opposed, theology and mysticism support and complete each other. One is impossible without the other. If the mystical experience is a personal working out of the content of the common faith, theology is an expression, for the profit of all, of that which can be experienced by everyone... There is, therefore, no Christian mysticism without theology: but, above all, there is no theology without mysticism. It is not by chance that the tradition of the Eastern Church has reserved the name of "theologian" peculiarly for three sacred writers of whom the first is Saint John, most "mystical" of the four Evangelists; the second Saint Gregory of Nazianzus, writer of contemplative poetry; and the third Saint Symeon, called "the New Theologian," the singer of union with God. Mysticism is... the perfecting and crown of all theology... theology par excellence.Or as my own beloved theological mentor, Fr John Behr, expressed it once to me: St John is called "the Theologian" because he "theologized" (= spoke of as God) the Word; St Gregory "theologized" the Holy Spirit; and St Symeon "theologized" the Divine Light.