The season of Lent gives almost unparalleled opportunity for preachers to placard before their auditors the Cross of Christ and beckon Christians to take up their cross and follow Him.
So, look . . . if you want to rely upon works of the Law to lay claim to the title "child of God," you can't. To be under the Law is to be a slave, and slaves are not sons.
Paul shows that the Law was never intended to save, but that salvation comes only through promise. The Law merely served as an instructor until the coming of the promised Christ.