I have no idea what kind of report you are looking for. Historical, contemporary, from a religious or social angle, etc.
If it's contemporary, why don't you look at the current exodus out of traditional churches and into megachurches? Those huge churches are nondenominational, they tend to be very socially conservative, use a high-tech delivery like a stage show, and they tend to be cash cows too. It's an interesting trend for sure.
If it's more historical, how about the initial differences between catholicism and lutheranism? Maybe compare it to the differences that are present today, if there is enough room in the report?