13 But we ought always to thank God for you, brothers and sisters loved by the Lord, because God chose you as firstfruits to be saved through the sanctifying work of the Spirit and through belief in the truth. 14 He called you to this through our gospel, that you might share in the glory of our Lord Jesus Christ. 2 Thessalonians 2:13-14
It’s rare that we get to share in the glory of the Lord Jesus Christ because after all, He is the second person of the Holy Trinity. But Paul noted that we do that because of the gospel. And he said that we were firstfruits. Firstfruits of what exactly? The sanctifying work of the Spirit.
In Bible School we learned it like this, we are saved, we are being saved, and we will be saved. We are saved from eternal damnation, we are being sanctified or set a part day by day, and in the latter days our salvation will be completed when we are in heaven. The point of this passage is the sanctifying work of the Holy Spirit in our lives. He is setting us apart and working in us day by day. We would do well to consecrate our lives to him each day. Only by His power can we conquer sin and live a victorious life.