Yes, there should be a wall between church and state.
However, I disagree with the statement, religion _absolutely belongs in schools. Students should study religion as part of cultural studies because it's such a huge part of our social interactions. Religious students should have accommodations granted, such as Muslim prayer time (and their Friday holy day), Sikh head coverings, etc, and students should learn about why these accommodations are important.
At least in the US, we have a constitutional amendment that bans the government from making any law preventing free exercise of religion, and to me that means restricting expression within schools. It also bans the government from establishing a religion, and to me that means giving preferential treatment in schools to any particular religion.
Religion should absolutely be a part of education in our schools, and it should absolutely be separated from government. These are absolutely compatible.