‘But before faith came we were kept in ward (kept under restraint) under the Law, shut up unto the faith which should afterwards be revealed, so that the Law has been our custodian to bring us to Christ that we might be justified by faith. But now that faith has come we are no longer under a custodian.'
Before this faith came then, we were kept in restriction under the Law, held under restraint like young children, until the way of faith should be revealed. The Law was like a pedagogue, a slave custodian, given responsibility to watch over a child's conduct, discipline him and take him to and from school and generally watch over him. But he could not make him do what he ought to do. And he was often someone from whom the child longed to escape.
But now things have changed for the faith has been revealed, and the Law as our moral tutor and disciplinarian has brought us to Christ so that we could be reckoned as righteous by faith. And now his task is finished. For having come to Christ we no longer require a moral custodian, for He is now our all and we are complete in Him (Colossians 2:10).
Note the continued reference to ‘faith' or ‘the faith'. The latter is the message of the Gospel, the former the response to that message. It is not always clear which idea is prominent, but the two always tie in together.
‘Kept under restraint.' In Galatians 3:22 it is sin that keeps us under restraint, here it is the Law. But this is because sin receives its power from the Law (1 Corinthians 15:56; Romans 7:13).
‘But now that faith has come we are no longer under a custodian.' This does not indicate a new dispensation. It rather reverts back to the time of Abraham. The Law was a temporary measure for Israel, which did not apply before the time of Moses, and which now no longer continues to apply in its judicial form, although still valid as an example. Now that Christ has come man can go back to the way of faith. The schoolmaster is no longer required for it has been replaced by the Master. As Abraham could look to God, Christians can look to Christ and be declared righteous by faith. The Law's main function has ceased. It has been replaced in the crucified One in Whom the Christian lives, in Whom he is declared righteous, and through Whose power and example he now walks before God.