This is my humble opinion;
1. There is no god
2. Religion is the reason of many wars.
3. Religion is used, and has always been used to control weak people.
4. Religion has nothing to do with knowledge, it is just story telling, comparable with Santa.
5. Religion is never tolerant. It is always making a difference between us and them.
In short, it is poison!
Since I am a recent high school student, I believe I have some extremely credible knowledge on what exactly 'Religious Education' is as a subject. The problem with the subject is the fact that education is primarily for children. Plenty of children already have religious beliefs rammed down their throats at home, and do not need the same to be done by any teacher. Children will find ways of learning about different religions and cultures through socialising with others, which generally will create a much more rational and free mind for any child experiencing new things in the world. To explain further, religion is a very sensitive subject, and children need to learn about it through experiencing the effects of it, and not simply being told about it.
No religion should be taught as absolute truth. It should only be taught in a historical sense. It is a fact that religion has had a major influence in human history. You can't just teach one religion however. At least the big ones need to be discussed equally. Children need to be taught how to think critically and for themselves. That way they can decide for themselves what they want to believe in.
Regardless of your beliefs, religion has had a profound effect on the human species. Religion should definitely be taught from the historical perspective for this reason. Though of course, education should be taught in such a manner that is unscientific or unhistorical to fit the beliefs of any one religion. IE: shouldn't say that species do not evolve just because the religion doesn't allow for it in the canon.
Education should not be free of religion, because of the importance of various religions upon the history of civilization. It is appropriate to teach the importance of religion in affecting human culture and politics. However, teaching students to be religious, such as leading prayers or giving one religion preference over another is not appropriate for an public educational setting. That is best left to parents, churches or religious schools.
I do not think that simply avoiding the subject of religion is an acceptable approach from an education standpoint. There should be ways of discussing everyones different walks of life without appearing to be preaching one particular lifestyle. Theology classes should be a required course in social studies, as if we are going to be a peaceful happy world of loving humans, we have to learn how each other grows and lives. Even if we don't agree with their way of life, we should learn to respect each other.
Religion is such a huge and central part of life and history that it should not be excluded from education. It should be taught and respected. Understanding religion helps us to understand each other and the reasons we behave how we do. It's not something to be feared, but it should be respected.