Is holding a belief in something that is objectively wrong itself inherently a harm?

No specific examples will be given, as the specifics here aren't the point. I'm also not talking about consequences of holding "wrong" beliefs, nor in communicating them (knowingly or otherwise). I'm talking about whether unknowing self-deception (by continuation of holding the belief, not necessarily by origin) should be understood as a harm to oneself.

To clarify, I'm not asking if a belief can be harmful (as in capable of causing harm), but rather if it can itself be a harm.