I was looking for sources demonstrating Christianity as a test for Jews. My search began when I was reading Rambam in Mishneh Torah (Laws of Kings 11:4; English):
[...] Can there be a greater stumbling block than Christianity? [...] the intent of the Creator of the world is not within the power of man to comprehend, for His ways are not our ways, nor are His thoughts, our thoughts. Ultimately, all the deeds of Jesus of Nazareth and that Ishmaelite who arose after him will only serve to prepare the way for Mashiach's coming and the improvement of the entire world, motivating the nations to serve God together [...]
Are there sources with the view that Christianity is something like a test for Jews?