Conclusion
It is the task of anyone who hopes to shed light on a problem not to construct a theory to support his sympathies but rather to show by reason, example and analogy the inner unity of the entire Christian faith. Thus it is that this analogy between the Holy Communion of the Eucharist and the holy communion of married intercourse must reach its conclusion, namely, that in order for marital sexual intercourse to be a valid expression of marital love and thus a means toward growth in holiness, it must at least be free from abortive, sterilizing and contraceptive impediments to the transmission of life.
The comparison has been made that the two communions are similar because they are both the results of sacraments, both the result of sacrificial love, both an expression of bodily love, both a renewal of the covenant, both covenants sealed with a death to self. Because of this, just as each reception of the Eucharist is in itself a sacred reality signifying complete acceptance of the covenant, likewise each act of married sexual love is a sacred reality. It entails a renewal of the marriage covenant, an acceptance of each other regardless of the circumstances, even if this renewal should lead to sickness or to poorness or even to death itself. That degree of self-giving is certainly going to require a supernatural faith, a deep and abiding realization that only he who loses his life for the sake of Christ will find it, and that he who seeks his life will lose it.
The Christian must come to realize that it is only through a constant, ever-increasing gift of himself to God and neighbor that he can arrive at the true development of himself. The married couple must come to realize that their desire to increase their mutual love and self-development can be fulfilled only through the self-giving which they signified through their exchange of marriage promises.
In this manner, with every act of intercourse a renewal of the marriage covenant in which they pledged undying fidelity to each other regardless of the situation, the married couple enter into a truly holy communion, a true source of grace and the occasion of the fullness of married love.
[1] Pope Paul VI thoroughly rejected the totality thesis in Humanae Vitae. He concluded his argument against the “totality” argument in this way: “Consequently it is an error to think that a conjugal act which is deliberately made infecund and so is intrinsically dishonest could be made honest and right by the ensemble of a fecund conjugal life” (n.14).
This full article is available at
http://www.nfpandmore.org/Holy%20Communion%20-%20Eucharistic%20and%20Marital.pdf with the introduction explaining why John wrote this article back in 1966.