No, not at all. Bach didn't compose nothing but church music. That is true for one reason first, as Bach worked for aristocrats for many years and this has been no service for a church. It started with the first inconsiderable half year in Weimar, plus later when Bach spend the second longest era of his life at that court: a total of nine years for Duke Ernst in Weimar. There composing church music was not part of his job. From his second term in Weimar Bach moved to the Sovereign Leopold of Koethen-Anhalt. And here as well, Bach didn't compose as a churchly musician.
Some musicians however claim, that all music, that Bach composed mirrors his deep religiousness, that means even when he wrote secular music. Bach also composed funny music, played on festivals and on weddings - and those events were more related to cheerful and secular music than to the music which Bach wrote for the church service.
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