Gr. arrabōn, “earnest,” “down payment,” related to the Heb. ‘erabon, “pledge,” as in Gen. 38:17-20. This word was in common use among Canaanite and Phoenician traders. Arrabōn is found frequently in the papyri, for earnest money paid for a cow, for land, for a wife, etc. It is also used of an engagement ring. It constituted a down payment, a pledge that the full sum would be paid as promised. It thus ratified the bargain. The earnest was to be payment of the same kind as that stipulated for the full amount, and was regarded as an integral part of it. In case the transaction was not completed by the purchaser, the earnest money was forfeited to the seller.

 Paul here uses the figure of earnest money to illustrate the gift of the Holy Spirit to believers, as a first installment, an assurance of their full inheritance in the hereafter (see Eph. 1:13, 14; cf. Rom. 8:16). It is the Christian’s privilege to receive the settled conviction of acceptance with God as His adopted child at conversion and to retain it throughout life (see on 1 John 3:1), to accept the gift of eternal life (see on John 3:16), and to experience the transformation of character made possible by the indwelling of the Holy Spirit (see on Rom. 8:1-4; 12:2; cf. John 16:7-11). But the joy that comes when the will is attuned to God’s will (see on Ps. 40:8), when the heart aspires to the stature of perfection in Christ Jesus (see on Matt. 5:48; Eph. 4:13, 15; 2 Peter 3:18), and when there is an uninterrupted daily walk with the Saviour—this joy is the “earnest” of a greater and eternal joy in the earth made new.

 Paul enjoyed such an experience, as did those Corinthian believers who were truly converted (2 Cor. 1:21). Accordingly, the charge that he was guided by selfish motives in the change in his plans (v. 23; cf. vs. 15-17) was altogether invalid. An “earnest” is much more than a pledge. What is given as a pledge differs in kind from that for which it stands as a guarantee. Furthermore, the pledge is returned when the obligation it represents is met. In contrast, an “earnest” is part of the obligation itself. The “earnest of the Spirit” may be considered equivalent to the “firstfruits of the Spirit” (Rom. 8:23), which is a sample of what the harvest at the end of the world will be like.

 Earnest money is given when there is to be some delay in completing the transaction. Sons and daughters of God are made heirs to all the blessings of heaven as soon as they enter into covenant relationship with Him (Rom. 8:17; Eph. 1:3-12; 1 John 3:1, 2); and the “earnest of the Spirit” is given to them in token of that right. In a sense, they already live in heaven (Eph 2:5, 6; Phil. 3:20). True children of God, who have this “earnest of the Spirit,” are in no state of uncertainty as to whether God has accepted them in Christ, and has in readiness for them their eternal inheritance (see on John 3:16; 1 John 3:2; 5:11). But full and complete payment—actual admission to heaven—is deferred in order to provide time for the development of character, so that the children may be fully prepared for heaven. The Christian’s title, or right, to the kingdom of heaven automatically becomes his the moment he experiences justification by faith in the imputed righteousness of Christ; fitness for the kingdom is achieved through a lifetime of appropriating the imparted righteousness of Christ and applying it to the daily problems of the Christian life (DA 300; MYP 35).

 As the Holy Spirit imparts grace and power to overcome sin, the Christian experiences an “earnest” of the complete triumph and victory that will be his upon admission to heaven. Fellowship with Christ and with one another here on earth is likewise a foretaste of the fellowship of heavenly beings. Only those who have received the “earnest of the Spirit” can know what it is and what joy it brings (1 Cor. 2:11, 15). A knowledge of spiritual things comes only by experience. To those who lack such spiritual knowledge heaven is more or less unreal.

 Gr. sphragizō, “to mark with a seal,” “to seal,” “to authenticate,” “to confirm.” A seal is used to attest the genuineness of the document to which it is affixed. The “seal” that God places upon men and women acknowledges them as His sons and daughters, as established in Christ and dedicated to His service (v. 21). See on Eze. 9:4; John 6:27; Eph. 1:13; 4:30; Rev. 7:2, 3; 14:1.