Galatians moves from redemption through the Son and reception of the Spirit to sonship and heirship; Titus moves through mercy, Spirit-renewal, Jesus Christ, justification, and heirship.

Israel’s identity as God’s son and firstborn in Exodus provides major biblical background for Paul’s movement in Galatians from slavery to sonship and inheritance. The later argument develops the sonship theme in Christ and by the Spirit, so the connection is canonical rather than a direct quotation.

Hosea’s child/son and exodus language supplies a plausible biblical backdrop for Paul’s heir-under-guardians and redemption-from-slavery imagery.

Jesus addresses God as “Abba, Father” in Gethsemane; Paul uses the same bilingual address for the Spirit-created cry of God’s children.

Romans 8 closely parallels Galatians 4: the Spirit leads God’s children, produces the cry “Abba, Father,” and confirms heirship with Christ.