Through the Son's redemption, we become God's inheritance (Eph. 1:7, 11). The word inheritance indicates that something of God Himself has been wrought into our being. Otherwise, we, the natural man, can never be God's inheritance. We were just a heap of dust, and as such we had no value. But since Christ's redemption has imparted something of God into our being, we have something of God Himself within us. The redemption of Christ has worked something of God into our tripartite being through the dispensing of the divine life and element into us. Some divine "gold" has been imparted into our spirit. Something precious has been spreading into our soul. Eventually, the glory of the divine person will permeate our entire body. Then our whole being will become precious. This will make us an inheritance, something precious for God to inherit. God is expecting to inherit such a precious inheritance. God the Son's redeeming to make us the inheritance of God is so that He may head up all things in Himself at the fullness of the times, for the completion of God's eternal economy (Eph. 1:10).
Although God is precious, we may not have the assurance that He will be our inheritance. The sealing of the Spirit (Eph. 1:13b) assures us that this precious God will surely become our inheritance. Furthermore, He has given us a pledge to guarantee that this will happen. This pledge is the Spirit (Eph. 1:14a). The Spirit is kept within us as the guarantee.
This sealing and pledging is for our enjoyment through the divine, all-inclusive dispensing of the processed Triune God. This dispensing is unto the redemption of our body (Eph. 1:14b), which will be transfigured into a glorious body (Phil. 3:21), saturated with the glory of the Triune God through His ultimate dispensing.