User blog comment:B214/General Discussion/@comment-24098614-20170730194208/@comment-10330822-20170730220446

Well first, Shiva is a member of the Triumvirate, the three chief gods of the hindu faith. They represent the cycle of creation, preservation, and destruction. Shiva is the God of Destruction, so he is widely considered to be the "necessary death" of things to instill the space for creation. If you watch Dragon Ball Super, Beerus performs an identical role, destruction before creation.

Indra is the ruler of the Hindu gods. Similar to how Romans have Jupiter, Greeks have Zeus, and the Norse have Odin. Indra is their figure.

So, if Indra wants to war with Shiva, its like the ruler of the faith wanting to battle a manifestation of order. Indra may desire to increase his own status by warring with Shiva. Also, he may view Shiva as evil because destruction means death, and we know Indra is a self-righteous being, since he killed Vritra and Mahabali's father of the Asura, both of which seemed uninstigated.

To be honest, I feel Indra may feel and judge things "evil" because of what they represent; i.e. Evil Dragon, God of Destruction, Prince of Asura; and thus wish to destroy them out of some misplaced sense of self-righteous. In reality, he seems very arrogant and vain, and I, personally, would find it amusing if he was the first God Issei defeats.