"But on the negative side, stoicism’s Providential claim that everything in the universe is already perfect and that things which seem bad or unjust are secretly good underneath (a claim Christianity borrowed from Stoicism) can be used to justify the idea that the rich and powerful are meant to be rich and powerful, that the poor and downtrodden are meant to be poor and downtrodden, and that even the worst actions ar…
> For one, that all bad things are actually good is not a tenet of Christianity and is not in the Bible Just for my own learning, if it's not considered a tenet, why do I see this line of thought so often portrayed: "This is not bad. God made is so to test my faith."
1. Pedagogical (the one you mentioned) - Evil exists so that we may grow and learn. All evil will be used to create even greater good. Quintessential example would be the story of Job in the Old Testament.
2. Eschatological — Evil is a by-product of having any creation in time whatsoever, and will be fully restored at the end of all things. Another way of thinking of this one is that evil is "non-being", the absence of the good. A lack, a privation. Espoused by Augustine (and before him, Neoplatonism in general), and Aquinas.
3. Freedom-oriented — Evil (even natural evil) is a broken state of affairs caused by the freedom of people, who use that freedom against God. God nonetheless allows this because he allows us the dignity to choose. The official teaching of the Catholic Church. The straightforward reading of Genesis 2.
None of these say that "This is not bad" - Christianity acknowledges the existence of evil "as evil". However, with God's grace, evil may be healed or made to serve higher purposes.