You choose the domain of law which every human associates with order, peace, and stability. I choose madness which people associate with complete unpredictability and chaos/anarchy. It's only natural that our gods would be against each other.

Btw you playing a god whose domain is law pretty much forces you to be against chaos. Chaos is a state of lawlessness. No systems, no rules, and no boundaries all of which your god is pretty much lord of.

And if it makes you feel better M'arash will be against everyone else as well. He seeks to drive everything mad. The reason? It has to do with the gate he's seen. He wants to open it and believes madness/total chaos is the key.