“And you also were included in Christ when you heard the message of truth, the gospel of your salvation. When you believed, you were marked in him with a seal, the promised Holy Spirit, who is a deposit guaranteeing our inheritance until the redemption of those who are God’s possession to the praise of His glory.”(Eph 1:13-14)
The Holy Spirit is a down payment, deposit, seal this mean that God has given us His Spirit guaranteeing that He is coming back for us.
Beloved, let us look at it from a natural perspective; If I enter a store to buy a jacket that costs $80 but want to put the item on layaway, first I will have to leave down payment of $30 to secure my jacket, then I will be given a time frame to complete my payment and take my jacket home; if someone comes to the store and see my jacket and decides to purchase my jacket even with the full amount to pay for my jacket, that person would not be able to take possession of it because my down payment has secured my jacket until the time is expired. Likewise beloved God has given the down payment of the Holy Spirit and He has time that only He knows, (Matthew 24:36) that He will be returning ,so within that time the devil can never take possession of a believer because we are purchased by the precious blood of Jesus. The Holy Spirit guarantees our inheritance.
“Now it is God who makes both us and you stand firm in Christ. He anointed us, set His seal of ownership on us, and put His Spirit in our hearts as a deposit, guaranteeing what is to come.”(2 Cor 1: 21-22)