The question of religion is a good one. And it depends upon the definition that is used.
1. On one definition - religion is a viewpoint or belief system that includes a supernatural being or principle that is used per the Australian definition.
2. Another definition used is worldview - used broadly to include secular humanism as per the American understanding and all other non-Western points of view.
3. Religion is also defined - as to do with orphans and widows - charitable work.
4. Religion is also defined by some Christian folk as trying to earn your way to God. Christianity according to these Christians would not fall under the religion definition because salvation is a free gift of grace not something you earn.
Hence, depending upon which definition you use and who you are talking to - can quite easily give you a contradictory point of view.
I think each of these definitions has a practical use for religion and the context used will obviously provide how to use it.
In the three ways used above - that you have referred to me:
Christianity is the only true religion - it would fall under 1-3. When I say I don't agree with religion - I am using it in the sense of definition 4. And when I talk about abolishing it - I am referring to definition no 4. I might add that I disagree totally with the definition 1 but accept it in practice when discussing some discussions. One very practical problem of deleting the initial definition as a matter of law - is the idea of tax in the Australian system. I don't know how the American one deals with it - in such a broad definition. In Australia - churches don't generally pay tax if they are a charity and are doing charitable work. If the definition used took a much broader one - suddenly it would include anyone who simply considers themselves a worldview and the courts have generally dismissed such thinking.
I don't know whether this helps or not. But there you have it.