Our Scripture reading today is Ephesians 1:13-14.
Verse 14, "Which is the earnest of our inheritance until the redemption of the purchased possession, unto the praise of his glory."
The very moment we turned to Jesus Christ for our eternal salvation, we were in dwelt by the Holy Spirit of God.  No believer can have any more of the Holy Spirit than they do today.  Our aim should be that the Holy Spirit has more of us each day that we live.  The Apostle Paul refers to this as being, "Filled with the Spirit". (Ephesians 5:18)  
We read in verse 14 of the Holy Spirit being the "earnest of our inheritance".  This phrase means that He is the down payment for what we will have for all eternity.  We are not living in Heaven at the moment, but Heaven is as good as ours due to being sealed by God's Spirit.  “The seal is therefore the Holy Spirit Himself, and His presence in the believer denotes ownership and security.” (Gaebelein)  This promise from God gives us all the eternal security we will ever need.  God's Spirit will be in us until we die or until the return of Jesus Christ.  Praise the Lord!