He is guilty of nothing, except a willingness to exercise heroic virtue
That’s not what “guilty” means in a legal context. If you broke a law, were proven beyond a reasonable doubt to have broken the law, and had sufficient mens rea in cases where that matters, you’re guilty. Any virtue associated with the action doesn’t really apply here, though I suppose you can make an exception for jury nullification. It doesn’t even matter if the judgment was correct, as juries (and judges during a bench trial) can get things wrong. I’m aware that there are other meanings of “guilty”, but using them in this situation (he was judged guilty in the legal sense, but that’s “wrong” because he’s not guilty in a different sense) is a form of equivocation.
the state of Iowa found Cassidy guilty of being Christian.
Again, not how it works in a legal context. He was found guilty for his actions, not the belief system and/or worldview which motivated his actions. It might be *metaphorically* true if vandalizing statues (or specific symbols regardless of what form they take) was inherent and/or common behavior to Christianity and to no one else. This would be similar to how anti-loitering laws don’t specifically target the homeless, but they make being homeless essentially illegal. However, that’d be a pretty weird assumption.
It’s that in a rightly ordered society, […] Cassidy wouldn’t just get off without a fine, he’d be rewarded by the state. The spiteful mutant Luciferians would be the ones whose guilt would be correctly discerned and punished.
Oh, so you’re judging his supposed lack of “guilt” in the context of a hypothetical society with a very different set of laws which you wish existed? That’s bordering on “not even wrong” territory.