Holy Magic

Holy Magic (神聖魔法): Holy magic is, in essence, magic involving manipulation of spiritrons. It can be used for healing, resurrection, or means of direct attack.

Principles
As spiritrons are particles that could transcend space-time, controlling them requires immense computing power and thus cannot be achieved via normal means. The most efficient way to achieve this, is to establish a pact with a higher entity and borrow its computing power to cast the spells. The user doesn't need to gather magicules from the atmosphere, and it wasn’t affected by the magical strength within the user. If the user has the right knowledge and enough time for chanting, they could weave powerful magic without exerting a great deal of energy.

What it does require, though, is a pact forged with a "god". A god, for the purposes of this kind of magic, is an existence powerful enough wield the spiritrons. It isn’t dependent on the caster believing in this or that god, or some other divine concept.

In Luminous Faith, Luminous Valentine is a god for this reason. Even Hinata cast holy magic by borrowing Luminous' powers. It could work as long as the god consented in lending his/her power in some way, and the god himself/herself doesn't have to be able to use holy magic. Dragon Faithful are able to use holy magic due to their belief in Milim Nava, despite her not being able to use it at all.

As long as the individual is powerful enough and understands the mechanism, s/he can even cast holy magic without having a god as a medium, as proven by Luminous and Rimuru. Moreover, less powerful individuals who has access to sufficient computing power through their skills can also cast holy magic on their own to a certain extent, like Shuna who did it through her Unique Skill "Analyst" (though it is more efficient to borrow Rimuru's power).

It is not a requirement, but the "god" can push it even further if s/he is able to utilize "The Ultimate Secret of Faith and Grace," an art that allows power transfer in the "god's" name. Besides bestowing the ability to cast holy magic, the "god" can even tap into the network formed by his/her follower's mind to further expand his/her computing power. This in turn allows the "god" to cast large scale magic with minimal preparation and effort, which is another reason that Luminous amassed a large number of followers.

Usage
Holy magic are most commonly used for healing injuries. Higher level practitioners can even regenerate lost limbs or resurrect someone who just died. Beside healing, holy magic can also be used for offensive purposes. There are two ways to attack with holy magic — conjuring energy with holy attribute that annihilate magicules (harmless against humans, but deadly against monsters), or directly weaponizing spiritrons. Examples include:


 * Holy Purification Field: Creates a barrier that purifies all magicules within, weakening and eliminating all monsters inside.
 * Holy Cannon: Fires a bolt of holy energy.
 * Holy Ray: Fires a beam of spiritrons. An original magic created by Rimuru.
 * Disintegration: Summons an avalanche of spiritrons that annihilates everything caught in its range.

Trivia

 * Since holy magic is usually associated with the Western Holy Church and monster slaying, it is widely believed in-universe that monsters are not capable of using holy magic. Therefore, most characters reacted in shock when they see a monster casting it.