Traditional Christianity damns marriage by dubious comparisons, faint praise, and pragmatic functionality

In a world where marriage has been, over several generations; purposively and systematically weakened, subverted, and finally rendered meaningless; it is tempting to yearn for the comparative situation of traditional Christian marriage - for its legal clarity and moral strictness.  

Yet the Christian churches (excepting the CJCLDS) have, in my opinion, seriously trivialized the spiritual potential of marriage.  

And for a very long time. 

I take my example from The Book of Common Prayer, the Church of England Solemnization of Marriage: 

DEARLY beloved, we are gathered together here in the sight of God, and in the face of this Congregation, to join together this man and this woman in holy Matrimony; which is an honourable estate, instituted of God in the time of man's innocency, signifying unto us the mystical union that is betwixt Christ and his Church;

This is absurd! To justify marriage between two individual persons in terms of a (to my mind) exceedingly dubious and opaque comparison with a supposed "mystical union" between Christ and "his Church"! 

This is to "explain" the simple with the complex; the experiential with abstraction; the clear with the opaque.  

I cannot imagine that anybody who was doubtful about the validity or necessity of marriage would be persuaded by this - or would even understand what was meant by it. The analogy merely opens a can of worms rather than explaining anything. 

After all; what is this supposed mystical union of Christ and Church (which does not feature in the Fourth Gospel)? Exactly who is the MU between - I mean, what counts as "his" Church, and what is excluded? To be specific, which actual people of which particular Church can confidently be asserted to be parts of this mystical union? 

And given the gross corruption and dissent of all the Christian churches - who and what self-identified Christian institutions, and which parts of which institutions - ought to be ignored, and in what respects? 

...which holy estate Christ adorned and beautified with his presence, and first miracle that he wrought, in Cana of Galilee; 

This is bizarre. Is it seriously suggested that the institutions of marriage is justified because Jesus attended a wedding, and there performed a miracle? 

Using such an argument, all sorts of things might be justified. 

..and is commended of Saint Paul to be honourable among all men: 

Commended by St Paul? Well, if at all, only in the most grudging and negative way. Paul regards celibacy as the highest state, and did not allow marriage any positive spiritual value.

and therefore is not by any to be enterprised, nor taken in hand, unadvisedly, lightly, or wantonly, to satisfy men's carnal lusts and appetites, like brute beasts that have no understanding; but reverently, discreetly, advisedly, soberly, and in the fear of God; duly considering the causes for which Matrimony was ordained. 

Prudent advice, and nothing to disagree with here, but it would apply to life in general (e.g. eating and drinking) and any major life decisions (like choosing a job or purchasing a house) - and does not help explain why marriage might be "a good thing"

First, It was ordained for the procreation of children, to be brought up in the fear and nurture of the Lord, and to the praise of his holy Name. 

The difficulty is that this is first a biological justification merely; and secondly a sociological one - and alternative arrangements for procreation and raising children might be (and indeed are) proposed. 

Secondly, It was ordained for a remedy against sin, and to avoid fornication; that such persons as have not the gift of continency might marry, and keep themselves undefiled members of Christ's body. 

See above. This is an appalling non-justification - and contains the assumption that the avoiding sin (double negative theology) ought to be our primary motivations. 

If this were true - ultimately, it were better not to have been born, or to die before having the chance to sin.   

Thirdly, It was ordained for the mutual society, help, and comfort, that the one ought to have of the other, both in prosperity and adversity.

Unobjectionable, so far as it goes; but nothing spiritual about it - merely a matter of expediency; nothing to do with salvation or theosis. 

I regard such feeble advocacy and rationalization of marriage as a symptom of very deep and widespread spiritual problems. 

This represents a pitiful and significant inability to explain or advocate a thing that has been so obviously, to for so many people, as one of the most wonderfully positive and desirable things in human existence. 

It strikes me as evidence of a grossly inadequate theology that (even) rigorous and honest traditional Christian churches at their best have failed so badly to make explicit the spiritual value and desirability of something that has often been directly experienced and known.