After some more conversations with Father Jones/Saint Amadeus, I left to prepare for my hunt.
Each of the pillars was a being born of suffering, all once great or demonic beings that were forgotten and left to slumber by humanity after the [Age Of Beasts]. When the culprits of the [Purple Dawn] needed beings to guard and house the pillars of the ritual, they brought these beings to the capital and hid them in a forced slumber.
Whoever seeks to tear apart the [Purple Dawn] must not only destroy every pillar but also the core after it is weakened.
The way the ritual was set up reminded me of the demonic ritual at the De Auguste estate. Its complex setup was intended to make it futile to attempt to stop the ritual. Even if one tore down the pillars, the ritual could still continue, just to a lesser effect, meaning that the pillars were simply to delay others from reaching the core, so there was ample time for the ritual to proceed.