What was the purpose of the Holocaust?

There are many theodicies that I have personally encountered while thinking about the Christian faith. One is the Irenaean “greater-good theodicy” or “greater-good defense”. The Irenaean theodicy maintains that the world represents the best of all possible environments because it provides the conditions necessary for human moral and spiritual maturation. In most formulations of this theodicy, creation is viewed as unfinished insofar as human beings have not yet reached their full potential. The experience of evil and suffering is thus understood as needed for the process of human development, serving as the context in which individuals grow toward moral and spiritual completeness. Assuming this explanation, what was the purpose of the Holocaust? What greater good comes out from the Christian deity letting over 13 million people – among these about six million ethnic Jews – be tortured, raped and gassed to death by national socialists? Potentially making a few former national socialists feeling regret and coming to Jesus? The believer would then be forced to square that logic with the internal framework of a just deity. Some Christian scholars reject the Irenaean theodicy (e.g., D. Z. Phillips, who I believe was the first scholar to offer this exact argument against appeals to any greater good), because of these difficulties. A few explanations have been offered to me, apart from the “saving souls” defense. Another is the “soul-making” theodicy, that the Christian deity wants us to discover and embrace virtues like courage, charity, and a willingness to sacrifice out of free will. Scholars like C. Robert Mesle accurately point out that these seem valuable *only* because evil and suffering exist. If persecution, starvation and suffering were abolished, those particular actions would no longer be needed and so would lose their value. Therefore if soul-making explains suffering only as a means to produce such virtues, it is unclear what would be lost in a world without suffering. Therefore it seems that we are left with a deity that values virtue development, as a principle, higher than preventing or relieving the effects of a genocide, or a deity that values instrumentally valuable virtues higher than intrinsically valuable virtues. It also seems to reduce human lives to mere pawns in a grandiose cosmic plan, in which the individual and the value of the individual are completely set aside in order to for the Christian deity to achieve a collective plan for humanity. In a way, Irenaeus made God the ultimate utilitarian. A third defense I have encountered is the appeal to mystery or magic, which is an utterly defeating and non-meaningful response that does not explain anything and shuts down the conversation by moving the problem into the unknowable. I am curious to what different Christian sects and denominations view this issue, and if there are other ways to rescue the Irenaean defense without ending up in any of the three aforementioned categories.