What was the source of tension between Hindus and Muslims in India?

They have two separate religions. Their customs, traditions, culture, history, represent two different civilizations. That was the source of tension between the two.

India also shares a border with Pakistan and other predominantly muslim countries. There is also a region between pakistan and India known as Kashmir that has its ownership disputed by Pakistan. India and Pakistan have fought many times over this region. This leads to a lot of additional tension between the two religions.