The Holy Spirt came at Pentecost and Paul says in Ephesians 1:14 that He (the Spirit) “is the guarantee of our inheritance until we acquire possession of it, to the praise of God’s glory”. The translated “guarantee” means both a taste of, and a promise for, future blessings. We have a foretaste of the feast to come in the Holy Supper. We have a foretaste of our sonship even as we hope for the fulfillment of our sonship.
Martin Franzmann talked about our faith worked through the power of the Holy Spirit, as a personal hope centered on the Lord. Since it is centered on the Lord its confidence is based upon all that Christ is and all that Christ has done to bring us to life everlasting through His sacrifice and reigning at the right hand of God’s throne for us.
It was because of the guarantee of the Holy Spirit that Paul in all of his trails and difficulties could say “the Lord shall deliver me from every evil work, and will preserve me unto His heavenly kingdom: to whom be glory forever and ever”. (2 Timothy 4:18)