Esna is loyal to God and Empire, but neither fanatic to the point of blindness nor paritcularly loyal to all aspects of the Empire.
In this respect, he could be called highly idealistic, but patriotic only to a point. For example, he firmly believes that slavery in the Empire, once excised of the abuse and hypocrisy it is currently is riddled with, will gradually be accepted.
However, he's also perfectly willing to call out others in the Empire who, as he sees it, besmirch the Empire's image or contribute to the hatred aimed at it; he's also willing to (and has in the past) participated in military action against perpetrators of more flagrant or horrific abuses. In his mind, these actions, while they could be seen as counterproductive by some, are needed to bring the Empire into a new age of acceptance, both of other cultures and by the other empires.
However, he doesn't do this soley because he feels a need to shake things up in the Empire or likes things better his way - rather, he feels that the only way to perpetuate and expand the following of the Amarrian religion is to bring the Empire into a new age; to not do anything will only cause the Empire to become more hated and secluded, imperiling the chance of expanding the follwoing of God.