From Tim Hegg’s Commentary on Romans – Speaking on the term “Under the law” in Galatians 4:4-5

It is easy to see why many commentators have understood Paul’s use of “under the Torah” in these verses to simply mean “born as a Jew to redeem Jews.” That Yeshua was born to Jewish parents, and that the first events in His life were circumcision and appearance at the Temple is emphasized by the Gospel writers (cf. Lk 2:21ff). But the parallel with 3:13-14 is so close as to warrant a continuing theme, namely, that one of the roles of the Torah as it pertains to the unbeliever is that of condemnation (cf. 2Cor 3:7ff). The Torah condemns sin and thus the sinner. 

But was Yeshua born “under the condemnation of the Torah?” In one sense, He was not. As the perfect and holy Son of God, He did not partake of Adam’s sin, and as such, was not born a sinner (cf. Rom 5:12f). But in another sense, He was born for the purpose of carrying the condemnation of His people, and in this sense He was born “under the condemnation of the Torah” as it pertains to their sins. 

For Paul, the ministry of Yeshua was conceived of as primarily soteriological. His coming was not primarily as a teacher of Torah or of wisdom as much as it was to identify with the human condition (“born of a woman”) “in order that, by His identification with the human condition . . . , His death might be the price necessary to free them from the slavery endemic to that human condition . . .”(Dunn, Galatians, p. 217). In this regard then, we should most likely see Paul’s use of “born under the Torah, so that He might redeem those under the Torah” to be a reference to Jew and Gentile alike. Even though the Gentile has no sense that he is condemned by the Torah until such time as he hears the message of the Gospel, he is nonetheless in a state of condemnation. He is “under the Torah” in the sense of being under its condemning power. Likewise, the Jew, who may have never considered that the Torah would condemn him, is under the condemnation of the Torah until such time as he places his faith in the redemptive work of Yeshua. We may conclude that “under the Torah” in this context means “under the condemnation of the Torah.”