Whereunto he called you by our gospel - He made the gospel as preached by us the means of calling you to salvation. That is, God has chosen you to salvation from eternity, and has made the gospel as preached by us the means of carrying that eternal purpose into effect.
To the obtaining of the glory of our Lord Jesus Christ - That you may partake of the same glory as the Saviour in heaven; see the notes on John 17:22, John 17:24.