There are two types of marriage:
1. natural marriage
2. the Sacrament of Marriage
We might further divide natural marriages into those that take place between unbaptized human persons in general, and those that occur between Jews. For the natural marriages of the Jews occur under Jewish religious law, which is the law of God. However, in ancient times and still today, a marriage between two Jews is a natural marriage, not the Sacrament of Marriage.
To have a valid Sacrament of Marriage, the two parties must be a baptized man and a baptized woman. During the marriage ceremony, they must each give their consent; this makes the marriage ratified (‘ratum’), allowing them to have marital relations without sin. Then they must engage in natural sexual intercourse, so that their marriage is consummated (‘consummatum’). (There is also the proper form of the marriage ceremony, but that is another subject.)
The Blessed Virgin Mary and Saint Joseph were married, prior to the establishment of the Sacraments by Jesus Christ. At the time of their marriage, Mary and Joseph were each unbaptized; neither had the formal Sacrament of Baptism. Therefore, they could not have had the Sacrament of Marriage. The Church teaches that a person must first be baptized, in order to receive any of the other Sacraments, including marriage. Christ could not have established the Sacrament of Marriage before He established the Sacrament of Baptism, since only baptized persons can be validly and sacramentally married.
Consummation is also required for the full Sacrament of Marriage, which includes the bond of the Sacrament. Mary was ever-virgin, so she did not have a consummated marriage. There is also a pious opinion that Saint Joseph was a virgin. But in any case, their marriage was not consummated, and so there was no bond of the Sacrament of Marriage.
As Fr. Z. points out in a recent post, a non-consummated marriage, even between two baptized parties, can be dissolved for a just cause (by the Holy See). This would not be possible if the couple had the bond of the Sacrament of Marriage. If a couple have each given consent, so that the marriage is ratified (‘ratum’), but they have not yet consummated the marriage by natural sexual intercourse (‘consummatum’), they do not have the full Sacrament of Marriage yet, for they do not have the bond of the Sacrament that is broken only by death.
In the case of Joseph and Mary, they could not have had a valid Sacrament of Marriage at all: no baptism and no consummation necessarily implies no Sacrament of Marriage.
But Scripture says that Joseph was the husband of Mary, so they must have had a marriage. Could they have had a natural marriage?
In general, a natural marriage also requires consent and consummation. But the natural marriages of the Jews occur under the law of God, expressed in the Old Testament. And that Law allows for certain cases in which the couple are married under the Jewish Law, but without consummation. In Deuteronomy 22:22-29, a man who lies with a betrothed virgin is guilty of adultery, and is put to death. But a man who lies with a virgin who is not betrothed is punished, but not with death; for he is not guilty of adultery. The betrothed virgin is married under Jewish religious law.
Typically, this situation (married but not consummated) would occur because of the longstanding custom among the Jews that, after the betrothal ceremony, there was some length of time before the woman moved into her husband’s house and the marriage was consummated. And since the betrothal ceremony was the beginning of the marriage, Sacred Scripture allows for the possibility of a betrothed virgin. She is the wife of her betrothed, and her betrothed is her husband, under religious law, despite the lack of consummation.
“According to Jewish custom, marriage took place in two stages: first, the legal, or true marriage was celebrated, and then, only after a certain period of time, the husband brought the wife into his own house. Thus, before he lived with Mary, Joseph was already her ‘husband.’ ” (Pope John Paul II, Redemptoris Custos)
But in the case of the Blessed Virgin Mary, she and Joseph were married under Jewish religious law, but perpetually without consummation. Mary remained a betrothed virgin. So Mary and Joseph had a natural but unconsummated marriage, under Jewish law.
Is it possible for two baptized persons to have a similar type of non-consummated, but valid Sacrament of Marriage? This is something of an open question. Certainly, such a ratified, but not consummated, marriage does not have the bond of the Sacrament, which can be broken only by death. So it is not the full Sacrament of Marriage. I suggest that such a marriage is like the betrothed-virgin marriage of Mary and Joseph. Perhaps such a baptized couple would have the Sacrament in some sense, ratum but not consummatum. Indeed, in order for the first marital act, which consummates the marriage, to be holy, rather than gravely sinful, the couple would need to be married in some sense.