The symbol is also present on Satan's throne, inside a shape that seems to resemble the same structure right above, where the sits of the Sins are.

It might be far-fetched and over-thinked, but it could also explain why Satan is specifically viewed as a deity and pushes that idolatry compared to how the other Sins are viewed, exclusively Lucifer.

If the cross in Christianity is used to refer to Jesus and the Trinity as whole.  
In the inverted scenario, if applicated to the sits of the Sins, it would in a way reflect the division of placement, at least with how the lower Hellborns might see them: 

* **Satan**, the judge and closest thing for the people of Hell (excluded Sinners and Goetia) to a god, as the inversion of the **Father**;

* **Lucifer,** the King of Hell and the fallen angel that corrupted humanity, as the inversion of the **Son**;
* The remaining **five Sins**, who mainly spread their vices in Hell and on the Earth, act as the inversion of **Holy Spirit**, maybe captained by **Beelzebub**, who sits at the very center and basically rappresents, as the **Sin of Gluttony**, general over-indulgence;

It's also interesting to notice that the inverted cross was present on the shark priest seen in ***Exes and Oohs***, as well as the medical symbol used by the **Sloth Ring**.

**Important note:** in real life, the inverted cross actually symbolizes **Saint Peter**, the First Pope, who let himself being crucified upside down because he didn't see himself worthy to die the same way Jesus Christ did. Of course, as many other things, it has being reinterpretated as a satanic symbol.

I noticed that the inverted cross is used to symbolize the authority of the Deadly Sins and it's overly present in the courtroom. I do wonder if even the sitting of the Sins might reflect that and might also have a religious meaning in Hell [MORE BELOW]