In English, the word “until” typically means one thing: “up to a certain point in time, and no further.” But when we read the Bible, this may not always be a guarantee. The Greek word εως is almost always translated as “until” because that’s what it generally means. However, it’s not always exactly the same as we tend to think.
Take, for example, verse 8 of Psalm 112. In English, it reads, His heart is steady; he will not be afraid, until he looks in triumph on his adversaries. Clearly, the Psalmist does not mean that this person becomes afraid once he looks in triumph – that would be absurd! Rather, in this instance, “until” means “all the way through to the point” with the implication that it’ll still never happen. It’s as if there’s sort of a proving time – if the person does not fear up to that point, he’ll never fear thereafter either.
Okay, that’s interesting, but hardly a big deal, one might say at this point. On the contrary, this could be significant. With a clear example of a slightly broadened Greek meaning of the English translation “until,” this could broaden the meaning of a lot of passages in the Bible that we might otherwise take for granted.
A significant example is found at the end of chapter 1 of the Gospel of Matthew: but [Joseph] knew her not until she had given birth to a son. And he called his name Jesus. Typically, we’d read this and assume that Joseph didn’t make love to his wife, Mary, until after she’d given birth to Jesus. This is a natural way to read it, and makes perfect sense. And it would emphasize the fact that Mary was indeed a virgin when she gave birth to Jesus. But with the broader “lexical range” (breadth of meaning) that εως has, it’s also possible to read this sentence to mean that Joseph and Mary never made love together, and remained chaste their whole lives.
I do not point this out to prove the historic Catholic teaching that Mary was life-long virgin. Rather, I point this out to caution that this verse does not make a case for either side, and should not be used as conclusive evidence in serious debates over the subject.