What does it mean that believers are sealed with the Holy Spirit at salvation?
At salvation, after hearing the word of truth and believing the Gospel, believers are sealed and marked by the Holy Spirit Himself. This sealing is part of the salvation experience, and the indwelling Spirit is the earnest—a sufficient down payment guaranteeing the believer's inheritance until the redemption of the purchased possession.
Les explains from Ephesians 1:13–14 that after we heard the word of truth—the Gospel of our salvation—and believed, we were sealed with that Holy Spirit of promise. He says this is part and parcel of the salvation experience: we have been sealed and marked by the person of the Holy Spirit Himself. Verse 14 calls the Spirit the earnest, exactly like we use the term today. He is the down payment, a sufficient down payment to make sure the transaction is completed. So the indwelling Holy Spirit as a result of our salvation is the down payment of our inheritance, which we will have by being joint heirs with Christ, and it holds it until the redemption of the purchased possession. Les also notes that soul and spirit are redeemed in full—saved and redeemed completely for all eternity—but the body is left.
In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,