One of the key defined Marian doctrines for Catholics is the Perpetual virginity of Mary, or the belief that Mary was a virgin before, during and after he birth of Jesus. When we dialogue with Christians from outside the Catholic Church this belief does not strike them as intuitive. Many times they will bring up the verse from Matthew’s Gospel which reads;
When Joseph woke from sleep, he did as the angel of the Lord commanded him; he took his wife, but knew her not until (= Greek: heôs hou) she had borne a son; and he called his name Jesus(Matthew 1:25).
Following the normal understanding of the word “until” in English the verse seems to imply that Joseph and Mary began to have normal conjugal relations after Jesus was born. The Greek words heôs hou in Matthew 1:25 can be can be translated either: “until” referring to a past fact or “while” referring to a contemporaneous event. The grammar is also complicated by the preceding negative.
It is interesting to observe other passages of Scripture which employ the same construction in Greek. In Matthew 5:25 we read “Settle with your opponent quickly while (heôs hou) on the way to court with him. Otherwise your opponent will hand you over to the judge,. . .” Similarly in Matthew 14:22 we read “Then he made the disciples get into the boat and precede him to the other side, while (heôs hou) he dismissed the crowds.” In this last example if the words were translated “until” is would mean that Jesus continued to dismiss the crowd for the entire length of time it took the disciples to sail across the sea of Galilee!
The leading three volume critical commentary on Matthew notes on Matt 1:25:
“This retrospective observation does not necessarily imply that there were marital relations later on, for heôs following a negative need not contain the idea of a limit which terminates the preceding action or state (cf. Gen 49.10 LXX; Mt 10:23; Mk 9.1)” [W. D. Davies and Dale C. Allison, Matthew (International Critical Commentary) Vol 1, p. 219].
What seems intuitively true in English is not so clear in the Greek. The over-riding truth is that the Church remembered the life of Joseph and Mary and proclaimed that Mary remained Ever-virgin.