ISB ~ Galatians 4 v4

the time had fully come:History reached a climax with the birth and death of the Messiah (Mk 1:15; Eph 1:10). This was the predetermined date “set” by God the Father to confer the blessing of divine sonship upon both Israel and the Gentiles (Gal 4:2; CCC 422, 484).

born of woman:Emphasizes that Jesus shared in the human condition (Job 14:1; Mt 11:11). Giving birth and flesh to the Son of God makes Mary the Mother of God (CCC 495, 723). See note on Lk 1:43.

born under the law:Emphasizes Jesus’ link with Judaism and his messianic mission to rescue Israel from the slavery of the Law and its covenant curses (3:13; CCC 580).