The great thing about biblical analogies is sometimes they can work both way. The relationship between Christ and his Church can be symbolically represented by the relationship between husband and wife, and, on the other hand, the relationship between Christ and his Church can strengthen what does it mean to be husband and wife. Both could be explored in great length, but it is to the latter that we will dwell in more depth here.
Christ loves his flock. Love invites a response, and the appropriate response is trust. We might be suspicious at a cheap notion of love, and our suspicion is well-justified. That’s why love needs to be showed, proved and embodied: and “God shows his love for us in that while we were still sinners, Christ died for us.” (Rm 5.8) God has shown his love for us. And he calls and summons us for a response: “Come and follow me!” And to come and follow him begins in putting our trust in him. Putting our trust at the One who has lay down his life for us. Greater love has no one than that.
Reflecting such love, the husband is called to love and give himself to his wife. And, again, the response is trust. The wife puts her trust in her husband. In this sense I think we should understand the word ‘submit’ used by Paul. It is a form of love-and-trust relationship. The wife en-trusts her whole life to her husband. And to entrust her life is to give her life as well. In the end, we get a relationship of reciprocal self-giving. The husband loves his wife and give himself to her. In return, the wife trusts her husband and gives herself to him. Indeed, “it is more blessed to give than to receive.” (Acts 20.35)
In this sense, sex is an ultimate form of this love-and-trust relationship between husband and wife, of this reciprocal self-giving relationship. First, the husband does not seek to lord over his wife and seeks his own pleasure in this act. The self-giving nature of love compels him to serve her, to seek the well-being of his wife. Thus, in the act of sex, the husband gives himself for the sake of the pleasure of his wife. In return of such self-giving act, the wife trusts her husband and gives herself as well to him.
And earlier I said that it is an ultimate form of a love-and-trust relationship between husband and wife, because it involves our bodies. Christian Gospel is no Gnostic Gospel, which works purely in a spiritual realm and despises the physical realities. Incarnation upholds the sanctity of the physical realm. Indeed, the reasonable worship is to present your bodies as living sacrifice.
And this form of the love-and-trust relationship will only work if it is done in and only in the context of covenantal marriage. If it is done outside a marriage, there is no guarantee that each party will not leave his partner. To trust requires a guarantee that each party will stay faithful to his partner. And this guarantee is given in the form of a covenant. A bond. A vow of love. That’s why in many tradition the marriage is formalized by some kind of vow recited by the husband and the wife. The vow, in some sense, establishes the covenant between the two (which perhaps is physically represented by a dowry or a ring or other sorts of things). The husband promises to be her husband, the wife promises to be his wife. “I will be your God and you will be my people.” (Exo 6.7, Jer 31.33) What establishes the covenant between Christ and his Church, then?
First, the blood, which is the blood of the covenant, which has been poured out for many for the forgiveness of sins. He has shed his blood for us. Second, the Holy Spirit which has been poured out for us, which enables us to cry out, “Abba, Father!” And third, the water, which has been poured out for us at our baptism. The covenant between Christ and his Church is established by his blood, the water, and his Spirit (cf. 1 Joh 5.6-8). They testify of the Son and compels us to put our trust in him. Likewise, to return to the husband and wife relationship, only in the context of a covenantal marriage one would be able to give himself or herself completely to his or her spouse.
Speaking of testimony, it also explains the public nature of marriage. Because a covenant needs witnesses who can witness to the validity of the covenant. That’s why marriage is no private matter. It is witnessed by God, represented by the presiding clergy, by relatives and by friends, who will account for what the husband and the wife has said during the ceremony.
Finally, the vow perhaps also mirrors how usually a covenant entails stipulations for both parties, which would be followed by blessings for obedience and curses for disobedience. In this case, the stipulation, which is in the form of a promise, is to stay faithful in good times and bad, in sickness and in health, in joy as well as in sorrow. “Israel, I will make you my wife forever, showing you righteousness and justice, unfailing love and compassion, I will be faithful to you and make you mine, and you will finally know me as YHWH.” (Hos 2.19-20)