The Tamil Nadu Department of Archaeology has officially counted 44,121 temples in Tamil Nadu. With 72,138,958 inhabitants (2011), that is 1,635 inhabitants per temple. Germany has 84,270,625 inhabitants (2022) and 45,600 Catholic and Protestant churches. That makes 1,848 inhabitants per church.
Many estimate, however, that the actual number of temples in Tamil Nadu is much higher (between 200,000 and 300,000). In Germany, by contrast, all the churches have probably been counted.
Christian churches concentrate largely on the message of the Bible; other systems of knowledge are quickly set apart as conspiracy theories of secret orders such as the Templars. Hindu temples, by contrast, are based on the Agama texts, which have a connection to the sciences, cosmology, the arts, spiritual wisdom, architecture, music, ceremonies, urban planning, economics, Yogas, Yantra, Tantra, Mantra…
Temples in India are one of the many keys to knowledge thousands of years old, whose origins, even today, are not really clear. For the oldest texts in India, the Rigveda, are not just any textual testimony, but a highly complex system of knowledge of every kind.
How Yantra (the geometric form also found in temple ground plans), Mantra (the spoken/sung text), and Tantra (the ‘instructions,’ the teaching) are interwoven can be seen beautifully in the Gayatri Mantra. You can listen to it here: Gayatri Mantra by Manish Vyas
I would also like to link to the Vāstusāstra here, because an English translation is not easy to find:
Vastu shastra VL. 1: Hindu Canons of lconography &Paining (76mb, 822 pages)
Viswakarma Vastusastram: A Treatise On Town-planning Etc.
The standard work of art history on temples in India is here:
Kramrisch, Stella. 1946. The Hindu Temple Vol .I . http://archive.org/details/in.ernet.dli.2015.282158.
Kramrisch, Stella. 1946. The Hindu Temple Vol. 2. http://archive.org/details/in.ernet.dli.2015.40420.
Here, from page 32 of Vol. 1, is a diagram of the arrangement of the gods in the temple:
