Defend which God? There are billions of Gods in India. Each village has its own.
It was only during the bhakti movement that Ram and Krishna became popular as a socio-political opposition to Muslims.
Pre-Islamic India followed real saints like Bhuddha and Mahavir. Almost all old temples in India are dedicated to Shiv/Buddha/Mahavir. Ram and Krishna were not even known to the Indus valley civilization.