but knew her not until she had given birth to a son. And he called his name Jesus.
25. And knew her not This passage afforded the pretext for great disturbances, which were introduced into the Church, at a former period, by Helvidius. The inference he drew from it was, that Mary remained a virgin no longer than till her first birth, and that afterwards she had other children by her husband. Jerome, on the other hand, earnestly and copiously defended Mary’s perpetual virginity.
Christ's incarnation is mystery to be adored, not probed. The espousal to Joseph honored the marriage state and saved the virgin's credit; without it, the world would ask whether He was a harlot's son rather than a carpenter's. God guards the reputation of His children with jealous care.
AI summary
Commenting on Matthew 1:18-25
And knew her not,.... Or "but he knew her not", answering to the Hebrew 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, see Gen 4:1 and what has been used in nations and languages.