A local newspaper recently published a brief account of the Christmas story, and the writer explained that the parents of Jesus were unmarried, and their traditional society viewed that fact as shameful.

The situation concerning engagement and marriage was a little different in Jewish culture back then than it is in our society today.

What we do know is that Mary was betrothed, or espoused, to Joseph. They had not “come together” (or “known” each other, the Biblical way of referring to sexual intercourse) but Mary was already pregnant. When Joseph learnt about this, he was quite perturbed and got to thinking how he would handle this situation. In Jewish law of the time, a woman found in such circumstances was to be brought before the civil magistrate in order to be punished according to the law which requires her to be taken out to the gate of the city and stoned to death (Deuteronomy 22:23). Or if the marriage had already taken place, and the pregnancy more advanced than the date of marriage would allow for legitimacy, then she was to be divorced and publicly shamed. But Joseph was compassionate as well as righteous, and he was loath to take either course of action, whichever was apllicable. According to his deliberations, as we are informed, it was looking like the latter (to divorce her quietly - Matthew 1:19).

The Gospel according to Matthew tells it like this:

This is how the birth of Jesus Christ came about: His mother Mary was pledged to be married to Joseph, but before they came together, she was found to be with child through the Holy Spirit.

Because Joseph her husband was a righteous man and did not want to expose her to public disgrace, he had in mind to divorce her quietly. But after he had considered this, an angel of the Lord appeared to him in a dream and said, “Joseph son of David, do not be afraid to take Mary home as your wife, because what is conceived in her is from the Holy Spirit. She will give birth to a son, and you are to give him the name Jesus, because he will save his people from their sins.”

All this took place to fulfill what the Lord had said through the prophet: “The virgin will be with child and will give birth to a son, and they will call him Immanuel” - which means, “God with us.”

When Joseph woke up, he did what the angel of the Lord had commanded him and took Mary home as his wife. But he had no union with her until she gave birth to a son. And he gave him the name Jesus.
(Matthew 1:18-25, NIV)

From John Gill’s Exposition of the Bible comes the following commentary on this situation:

Verse 24: …and rising up from his bed or place where he was, [Joseph] immediately and without any delay, did as the angel of the Lord had bidden him; firmly believing that it was a messenger of God that was sent to him, and that this matter was of the Lord. Wherefore he took unto him his wife, that is, he publicly married her, whom he had before espoused, took her to his house, or continued her there, lived with her as his wife, and owned her to be such, and henceforwards had no more thoughts of putting her away.

Verse 25: “And knew her not”…. or “but he knew her not,” that is, had carnal knowledge of her, or copulation with her, though his wife. The words are an euphemism, or a modest way of expressing the conjugal act, and is a very ancient one, and what has been used in nations and languages.

The other record of these events is to be found in Luke’s Gospel where it is briefly said of Mary that she was “pledged to be married to him [Joseph] and was expecting a child” (Luke 2:5). However, John Gill’s Exposition of the Bible has this to say:

Verse 5: To be taxed with Mary his espoused wife…. Whom also he had married, though he had not known her in a carnal way; she came along with him to be taxed and enrolled also, because she was of the same family of David, and belonged to the same city:

Betrothal was, in Jewish law, valid marriage. If Joseph was to “give Mary up” or “put her away” he would have had to take legal steps to effect the separation. (Jamieson-Fausset-Brown Bible Commentary)

Smith’s Bible Dictionary discusses espousal and betrothal as follows:

The selection of the bride was followed by the espousal, which was a formal proceeding undertaken by a friend or legal representative on the part of the bridegroom and by the parents on the part of the bride; it was confirmed by oaths, and accompanied with presents to the bride. The act of betrothal was celebrated by a feast, and among the more modern Jews it is the custom in some parts for the bride. groom to place a ring on the bride’s finger. The ring was regarded among the Hebrews as a token of fidelity and of adoption into a family. Between the betrothal and the marriage so interval elapsed, varying from a few days in the patriarchal age, to a full year for virgins and a month for widows in later times. During this period the bride-elect lived with her friends, and all communication between herself and her future husband was carried on through the medium of a friend deputed for the purpose, termed the “friend of the bridegroom.” She was now virtually regarded as the wife of her future husband; hence faithlessness on her part was punishable with death, the husband having, however, the option of “putting her away.” The essence of the marriage ceremony consisted in the removal of the bride from her father’s house to that of the bridegroom or his father.
(Smith’s Bible Dictionary)

So although their marriage was not consummated prior to the birth of Jesus, the parents of Jesus were legally committed to each other by a prenuptial agreement which could be broken only by a formal process of divorce.