This is a broad topic, but people feel passionately about religion, so nearly anything regarding it can easily be controversial. You can narrow the topic down by asking yourself a specific question that clearly has both a "yes" and a "no" answer. For example, you could ask, "Is religion a force of good in the world?" Regardless of what stance you take, you will need to research both the good and bad things that religion has done in the world, so that you can support your side while countering the arguments that could be made for the other.
The major issue surrounding extremist groups is whether or not they should be allowed to publicly promote their beliefs. For example, groups like the Westboro Baptist church are known for their extreme stances against homosexuality and for picketing at funerals. You could use their activities as an example and argue whether or not Westboro and similar groups have the right to their activities. This question would also explore how far these groups should be able to go in order to promote their beliefs.
The issue of animal rights is another fairly broad topic. You could argue whether or not animals should have any rights and what rights they should have. Animal experimentation is an issue connected to this one that also tends to generate a lot of discussion. Should we use animals to test potentially dangerous drugs? Should we use them in experiments? Depending on how focused your paper needs to be, you could answer any number of these questions or choose one to focus your attention on.
Violence in media has been a controversial issue since there has been long-lasting media to communicate in. Arguments around this issue usually focus on whether or not violence in things like books, movies, video games and TV has a negative impact on people. For example, does watching violent television and movies promote more violence in the real world?