Catholic Answers senior apologist Jimmy Akin describes the ways in which the Church Fathers explained the perpetual virginity of Mary.
How did the Church Fathers explain the perpetual virginity of Mary?
The earliest theory we have on record that explains how Mary remained a virgin, and yet how there are individuals in the New Testament who were described as Jesus’ brothers and sisters, is recorded in a document from the second century. The document is known as the Protoevangelium of James.
It’s also sometimes called the Infancy Gospel of James, or even just the Gospel of James. And it deals with the early life of the Virgin Mary. That’s why it’s called the Protoevangelium or First Gospel. It deals with the series of events before the actual birth and ministry of Christ.
According to the Protoevangelium of James, Mary was a consecrated virgin. She had been pledged to the temple by her parents and served at the temple in Jerusalem.
But when she reached a certain point in her life, she began to be ritually unclean under the Jewish laws, and consequently she couldn’t stay at the temple.
She needed therefore a guardian, but because she was a consecrated virgin, she needed a guardian who wasn’t going to be interested in leading a normal married life with her.
And so a selection process was begun, and, as a result, Joseph, an elderly widower who already had a family and therefore wasn’t looking to raise another one, was deemed a suitable guardian for a consecrated virgin such as Mary.
According to this theory, according to the Protoevangelium therefore, the “brethren of Christ” were his stepbrothers through Joseph rather than the cousin idea that is commonly heard today.
Now, the Protoevangelium of James was written probably around the year 150—sometime in the middle of the second century—within a century of the Virgin Mary’s own life.
So, even though it’s not part of the Bible, and the Church does not consider it inspired writing, it nevertheless may contain some accurate traditions regarding Jesus’ family. And this could be one of them.
The second theory was popularized by St. Jerome when a conflict broke out in his day in the early 400s regarding Mary’s virginity. And according to St. Jerome, the “brethren of Christ” who are mentioned in Scripture are actually cousins or other relatives of that kind.
There is some support for this theory in the fact that Aramaic—the language spoken in Jesus’ day—does not have a word for cousin. You have to use circumlocutions such as “the son of my uncle” or “the daughter of my aunt” or things like that.
And some have suggested that the words brother and sister may have, at times, been used as synonyms for cousin. But that’s somewhat speculative.
In any event, St. Jerome popularized the “cousin” theory, and it’s one of the most common today.