Asylon is going to war to help our allies as well, we just don't need to lie about our intentions to recover lands we lost in the last war. Also, in the end everyone is fighting to avoid to see SA ruling Dwilight as they wish. While much people can enjoy the religion, and it's very good since it's the best religion BM have now, IG a lot of realms don't want to bow to the Elders and to realms like Morek and Astrum. This is not just about religion and Asylon is a realm of crazy warriors trying to fight a good war.
Personally, Henrich has good reason since Yeux (a parent) left Morek to found Averoth, a realm devoured by the theocracies.