The contrast presented in the previous chapter between imprisonment under the law (3:23-25) and new relationships in Christ (3:26-29) is now clarified by an illustration drawn from a household where sons were treated as slaves until they received the full rights of sons at the age of maturity. First, the slavelike condition of the sons while they were still minors is described and applied to the human condition (4:1-3). Second, the sending of God's Son to liberate slaves and make them sons is announced (4:4-5). Third, the full rights of sons are disclosed (4:6-7).