That is just wrong to say Christianity is not a religion. Buddhists, Hindus, Moslems, and Shinto’s are religions that compete with Christianity. Each religion has its own set of truths. To think there is only one truth is arrogant. The only fair way to examine each religion is to stand back and take a tolerant secular approach to researching them, then choose the one that makes the most sense or meets most of the criteria that you select that defines a good religion.
It should read that from time to time each religion manufactures its "truths" to suit the beneficiaries. It wasn't so long ago that Mormons rejected dark skin people.
Religion is inside each one. No outside. Churches are not religion. They are a human product riddle of mistakes like all human life lived from the self (ego).