The mission of the Son and that of the Spirit are spoken of in vv. 3-6 in parallel terms: "God _sent forth_ His Son--_sent forth_ the Spirit of His Son," the former into the world of men, the latter "into" their individual "hearts." The second act matches the first, and crowns it. Pentecost is the sequel of the Incarnation (John ii. 21; 1 Cor. vi. 19, 20). And Pentecost is repeated in the heart of every child of God. The Apostle addresses himself to his readers' experience ("because _ye_ are sons") as in ch. iii. 3-6, and on the same point. They had "received the Spirit:" this marked them indubitably as heirs of Abraham (ch. iii. 14)--and what is more, sons of God. Had not the mystic cry, _Abba, Father_, sounded in their hearts? The filial consciousness was born within them, supernaturally inspired. When they believed in Christ, when they saw in Him the Son of God, their Redeemer, they were stirred with a new, ecstatic impulse; a Divine glow of love and joy kindled in their breasts; a voice not their own spoke to their spirit--their soul leaped forth upon their lips, crying to God, "Father, Father!" They were children of God, and knew it. "The Spirit Himself bore them witness" (Rom. viii. 15). This sentiment was not due to their own reflection, not the mere opening of a buried spring of feeling in their nature. _God sent it_ into their hearts. The outward miracles which attended the first bestowment of this gift, showed from what source it came (ch. iii. 5). Nor did Christ personally impart the assurance. He had gone, that the Paraclete might come. Here was another Witness, sent by a second mission from the Father (John xvi. 7). His advent is signalised in clear distinction from that of the Son. He comes in the joint name of Father and of Son. Jesus called Him "the Spirit of the Father;"[114] the Apostle, "the Spirit of God's Son." [114] Matt. x. 20; Luke xi. 13; John xiv. 16; Acts i. 4, 5. To us He is "the Spirit of adoption," replacing the former "spirit of bondage unto fear." For by His indwelling we are "joined to the Lord" and made "one spirit" with Him, so that Christ lives in us (ch. ii. 20). And since Christ is above all things the Son, His Spirit is a spirit of sonship; those who receive Him are sons of God. Our sonship is through the Holy Spirit derived from His. Till Christ's redemption was effected, such adoption was in the nature of things impossible. This filial cry of Gentile hearts attested the entrance of a Divine life into the world. The Spirit of God's Son had become the new spirit of mankind.