Seems to me that even supposedly deontologic arguments usually have some (not always explicit) explanation, such as "...because God wants that" or "...because otherwise people will not like you" or maybe even "...because the famous philosopher Kant would disagree with you".

I'm told that these explanations fall under the realm of meta-ethics. As far as I (not being a deontologist) can tell, all deontological ethical systems rely on assuming some basic maxim - such as "because God said so", or "follow that rule one would wish to be universal law".

I don't see how deontology would work without that maxim.

Assuming my model of deontologists is correct, then their beliefs are like "Don't torture people, no matter what the benefits of doing so are, because God does not want you to torture people!" Then all it needs is a charismatic priest who explains that, for some clever theological reasons, God actually does not mind you torturing this specific person in this specific situation.

For a historical example of exactly this, see the Spanish Inquisition. (They did torture people, and I did once come across some clever theological reasons for it, in which it is actually quite difficult to find the flaw).