What were the religious beliefs and practices of the Harappans?

The religious beliefs of the Harappans and by extension the entirety of the Indus Valley Civilisation is a matter of debate and speculation that continues to this day. 

Archaeologists who unearthed Hrappa and Mohenjo-daro were perplexed at the lack of temple structures in the cities. The Indus valley script is yet to be deciphered and once it has been deciphered, further light will be shed on the religious beliefs of the IVC.

However with certain evidence such as symbols (such as the discovery of seals bearing the swastika mark) and deity figures, it can be believed that the Harappans worshipped gods and goddesses and had religious beliefs. But due to sparsity of evidence, it is purely speculative at best.

For further reading check the following articles:

• Prehistoric Age in India
• Indus Valley Civilization
• Prehistoric Rock Paintings