What does it mean that the sealing of the Holy Spirit is the earnest of our inheritance?
The sealing of the Holy Spirit is the earnest, or down payment, of our inheritance, until the redemption of the purchased possession. It means the soul and spirit are already redeemed, but the body still awaits final redemption, when we become complete and ready for all eternity.
Les explains from Ephesians 1:14 that the sealing of the Holy Spirit is the earnest, the down payment, of our inheritance until the redemption of the purchased possession. He notes that the soul and spirit are already redeemed, but what is waiting is the redemption of the body. Then, turning to Romans 8, Paul says everything is moving to the day when we will have that final redemption of the body, and then we will be a complete entity, ready to go into all eternity.
Which is the earnest of our inheritance until the redemption of the purchased possession, unto the praise of his glory.