But before faith came - That is, the system of salvation by faith in the Lord Jesus. Faith here denotes the Christian religion, because faith is its distinguishing characteristic.
We were kept under the law - We, who were sinners; we, who have violated the Law. It is a general truth, that before the gospel was introduced, people were under the condemning sentence of the Law.
Shut up unto the faith - Enclosed by the Law with reference to the full and glorious revelation of a system of salvation by faith. The design and tendency of the Law was to shut us up to that as the only method of salvation. All other means failed. The Law condemned every other mode, and the Law condemned all who attempted to be justified in any other way. Man, therefore, was shut up to that as his last hope; and could look only to that for any possible prospect of salvation. The word which in this verse is rendered “were kept” ἐφρουρούμεθα ephrouroumetha, usually means to guard or watch, as in a castle, or as prisoners are guarded; and though the word should not be pressed too far in the interpretation, yet it implies that there wasa rigid scrutiny observed; that the Law guarded them; that there was no way of escape; and that they were shut up. as prisoners under sentence of death, to the only hope, which was that of pardons.
Unto the faith ... - That was the only hope. The Law condemned them, and offered no hope of escape. Their only hope was in that system which was to be revealed through the Messiah, the system which extended forgiveness on the ground of faith in his atoning blood.