We all must agree those are some magnificent passages.
2Thess 2:13-15
But we are bound to give thanks to God always for you, brethren beloved by the Lord, because God from the beginning chose you for salvation through sanctification by the Spirit and belief in the truth, to which He called you by our gospel, for the obtaining of the glory of our Lord Jesus Christ. Therefore, brethren, stand fast and hold the traditions which you were taught, whether by word or our epistle.
There is every reason to believe that being chosen/election is the driving force and reason for what follows.......belief.
Please note that Paul is thanking God for the belief that the Thessalonians now possess.
Paul is NOT thanking the Thessalonians for their faith, their believing and their works.
It is self evident that God Himself is taking the initiative in doing the works here.