FYI, this is a recent statement by Ecumenical Patriarchate Bartholomew (spiritual head of the Orthodox Church) when he was asked how gay marriage (and not homosexuality itself) threatens the family:
The Church, my beloved parents and children, and subsequently the family, which consists lawfully and by the command of God of men and women, and the children acquired, is not a foundation or association or a simple organization, but a Body, as it is wonderfully depicted by the Apostle Paul. And this parallelism is accurate and true. Church and marriage. Husband and wife. Body and its members.
This community, signified in the Mysteries and in the obedience of Faith, both in the Church and in the family, is sanctified and mystagogued through the Mystery of Marriage, which, according to the Fathers, is a mystery of co-creation, and the ontological link of love with the Head of the Body, to ensure health and life, which is salvation and sanctification.