As you can read in one of the comments, “No wonder people went to church in those days…”.
Bach composed this cantata in 1731 in Leipzig for the election of the city council. It is about thanksgiving to God for the prosperity of the city, request for future blessings and praise of his power.
The cantata is one of the few sacred cantatas with an introductory instrumental sinfonia. This is an arrangement of the Preludio from Bach’s Partita in E major for violin, BWV 1006. The organ takes over the virtuoso solo part, the orchestra has an accompanying function.
More on Wikipedia (in German).