How do I make the concept of "Divine Black Magic" work?

So a random thought just came to my mind and now I want to implement it into my fantasy world but I haven't really completely fletched it out.

What if black magic could be divine?

And not like that it comes from an evil god or a misleading name for divine magic from the god of night. I'm talking about actual evil black magic but from a divine holy source.

So here's how it works:

This unique form of magic is more precisely called "Sin Magic" and it originates from the ugly side of every divine god.

Despite what the believers think, gods themselves are also capable of sinning in the same way as humans. They may smite/curse innocent people out of jealousy/boredom or commit horrible acts against other gods out of lust/anger.

However, despite all of these tales being recorded. The original point is ignored and swept under the rug as the believers give their blind faith to their dieties.

Paladins and Priest who become fully aware of the ugly truth gain the ability to cast Sin Magic which is a twisted and more cruel version of the god's divine spells and domain.

For example: The servants of the goddess of fertility and harvest who can use sin magic can cause maize crops to violently and slowly sprout from the bodies of live victims.

And that's all it.

Now I don't know about the social and religious implications this would have cuz I'm stuck and constantly wavering between having Sin Magic casters being ostracized from their religion for defiling the image of their god.

Or this act could rather be strangely accepted and would have an entire sect for these type of believers who or more akin to fanatic cultists.

Or maybe they could be serve as a group of secret assassins who do all of the dirty work of the god and the church.

Please help and tell me what should I do, I haven't even come up with a name for the Paladins and Priests who use Sin Magic so it would be wonderful if you could drop in some suggestions.