If something is true, then there's no reason to command someone to believe it. If it is true, then one need only show why it is true. Surely an explanation is more powerful than a command.

Yes, but if someone is incapable of understanding the explanation, or the explanation cannot be formulated in a non-ambiguous, satisfactory way, then that someone can only learn that truth by experience. In that case, those who understand the truth can only serve as a guide while the individual in question learns through experience.


And surely a demonstration can be more powerful than an explanation...

Talking past each other.

First off, it is impossible to not believe. Action dictates this. Universal skepticism may follow from the fallibility and the uncorroborative nature of human understanding, but for humans to be humans, that is to act, one must have beliefs about the past, present, and future state of the world.

As nerdfiles has said, no one can enforce belief, one can only enforce insincerity. To the counter, one cannot choose disbelief, one can only express insincerity.

Truth impresses itself upon the mind by way of sensation, reason, or argument. At least we understand it as so.

Finally, when we speak of what one "should", we speak of morality, and we state that one should attempt to be "good" and act "for the good". In order to act with any purpose (to promote the good), we must have some belief about the world and how our actions will change the world. Negligence to the truth is negligence to moral duty.

So, if you do wish to speak of shoulds, I propose that moral obligation supports our demands for belief.

Now, if you only mean that one should not promote one belief above another on any grounds other than the justifications thereof, I do not know who could argue against you and still hold any coherent understanding of belief and truth.