Note 1 at Gal. 4:1: Paul is now giving a human illustration to show the state of spiritual immaturity that one experiences by being under the law. Paul states that being under the law is no better than being a slave, whereas faith in Christ brings us into a position of a full-grown son (Gal. 3:26).

It is sad to say, but most Christians have never graduated into the sonship that Paul is describing here. They are still serving God with an Old Testament law mentality which is not pleasing to God (Heb. 11:6) and is oppressive to them (see note 4 at Rom. 3:19, p. 757). The truth is that sonship is theirs. It's been provided for them freely through Christ. But it doesn't happen automatically. We have to renew our minds (see note 9 at Rom. 12:2, p. 826) to take advantage of this blessed relationship.