How did Bach’s church cantatas use the chorus and a closing chorale?

In the church cantatas of Johann Sebastian Bach, the chorus plays a prominent and complex role, often featuring music of a technical difficulty comparable to the accompanying instrumental forces.1

During his early years in Leipzig, Bach developed the "chorale cantata," a specific form that utilized the chorus in two distinct ways:

• Opening Movement: These works typically begin with an elaborate choral fantasy based on the first stanza of a hymn.2
• Closing Chorale: The cantata concludes with a simple, richly harmonized setting of the hymn's final stanza. In these closing movements, the choir is supported by orchestral doubling or accompaniment, and the congregation was expected to join in the singing.312

While Bach never composed an original chorale, he masterfully adorned well-known hymn tunes with complex harmonies, integrating them into the broader structure of the cantata alongside recitatives and arias that paraphrased the intermediate stanzas of the text.32