The Perpetual Virginity of Mary

The Biblical evidence. To quote:

It is no secret that ancient Judaism, like the Church, prized the goods of marriage and family. But Judaism had room for celibacy too, if practiced for religious reasons. The best known example is the rabbi named Jesus of Nazareth. In addition to Him, we also have the example of the prophet Jeremiah (Jer 16:1-2), St. Paul (cf. 1 Cor 7), and St. Philip's "four unmarried daughters, who prophesied" (Acts 21:9). Beyond the record of Scripture, we also find Jewish groups like the Essenes and the Therapeutae, who likewise consecrated themselves to virginity. Consecrated virginity was not unheard of in ancient Judaism.