The first mortals that met the god were punished.
For their unworthy eyes, they were blinded.
For their sinful lives they were made pure
For their unfaithfulness, they were made loyal.
The purifiers/purified are amalgamations that serve the god of light. They are made from the souls of the damned as punishment for not following the god and/or breaking his tenants. They are contorted and forced together with multiple other souls until one is amalgamated. Once forced together, their only duty and goal is to purify those deemed damned by the god, they have no personality or individuality. The only emotions they seem to express is through the multiple eyes on the rings around them that represent every soul in the amalgamation, they seem to scream out with the terror in their eyes.
Their attacks are pin point based aoes that are accurate, they breathe holy fire, use radiant magic and can coat themselves in holy fire that burn their attackers.
They cannot be blinded and are weak to necrotic and lightning. They are resistant to bludgeoning, piercing, and slashing.