A marriage which does not constantly crucify its own selfishness and self-sufficiency, which does not "die to itself" that it may point beyond itself, is not a Christian marriage. The real sin of marriage today is not adultery or lack of "adjustment" or "mental cruelty." It is the idolization of the family itself, the refusal to understand marriage as directed toward the Kingdom of God. This is expressed in the sentiment that one would "do anything" for his family, even steal. The family has here ceased to be for the glory of God; it has ceased to be a sacramental entrance into his presence. It is not the lack of respect for the family, it is the idolization of the family that breaks the modern family so easily, making divorce its almost natural shadow. It is the identification of marriage with happiness and the refusal to accept the cross in it. In a Christian marriage, in fact, three are married; and the united loyalty of the two toward the third, who is God, keeps the two in an active unity with each other as well as with God. Yet it is the presence of God which is the death of the marriage as something only "natural." It is the cross of Christ that brings the self-sufficiency of nature to its end. But "by the cross, joy entered the whole world." Its presence is thus the real joy of marriage. It is the joyful certitude that the marriage vow, in the perspective of the eternal Kingdom, is not taken "until death parts," but until death unites us completely.Schmemann is rightly claiming here that marriage is untintelligible outside the Church, but it's even more unintelligible without marriage is placed inside the very mission of God in the world.
The mission of God is what gives marriage its proper sense of itself.
Here, Schmemann is exposing one of the realities of our cultural understanding of marriage: Most folks think marriage exists for me and my spouse, to make us happy. But Christians know just how idolatrous that is. Marriage that turns in on itself for meaning is a marriage that must be subject to what Lewis called "a severe mercy".
Christian marriage doesn't exist for the benefit of the two people in the marriage; it's for the benefit of the world, that God would be glorified. The main purpose of marriage is not the enjoyment of the two people who are married -- the main purpose of marriage is to glorify Christ as we participate in the Mission of God. Anything less is making an idol out of marriage.