"The Mystery of Faith: An Introduction to the Teaching and Spirituality of the Orthodox Church" by Bishop Hilarion Alfeyev

"It would be heresy to insist on the necessity of the salvation of all, as if this were compulsory for both God and human beings, but it is not a heresy to believe in the possibility of the salvation of all, and to continue to pray and hope for that. Together with St Paul, Gregory of Nyssa, Maximus the Confessor and Isaac the Syrian, this belief was held also by St John Climacus, who says, 'It is not impossible for all to be saved and reconciled with God.'" (221)