Eph 1:14

1:14 guarantee. The Spirit is not only a fulfillment of God’s promise to indwell His people, but also is a guarantee that He will bring them to their final inheritance. As a down payment or first installment on their full redemption, the Spirit is a foretaste of the glory of the age to come (Rom. 8:18–23).

possession. The Old Testament teaches that God chose a people as His inheritance (Deut. 32:9; Ps. 33:12) and purchased them out of bondage to become a prized possession (Ex. 19:5; Deut. 7:6). Peter agrees with Paul’s striking application of this idea to Gentiles as well as to Jews (1 Pet. 2:9).