[graemep]

Lots of Asian countries have a common culture that spans groups following different religions: Indonesia, India (and particular Indian regions), Sri Lanka etc.

Also, most of the major religions spread to different cultures a long time ago: A thousand years ago a Russian and a South Indian could have both not only been Christians, but both Eastern Orthodox, or an Indonesian and a Libyan could both be Sunni Muslims, or a Sri Lankan and Laotian could both be Theravadan Buddhists.

If people of disparate cultures could share common beliefs, sure religion and culture have always been separable. Especially pertinent to your examples are the South Indian Christians who have undoubtedly shared the culture of the Hindu majority for 2,000 years.

[Silentio]

What you say is true, as far as I know. It is entirely possible to share the culture of the people who one lives nearby and yet practice a different religion. It is also true that this has been going on for a long time. In the case of the spread of Abrahamic offshoots (Islam and Christianity), a couple of thousand years. In this sense religious expression has always been fluid. However, I think that is different than viewing religion as an object. It is a modern move to split culture into many different categories: public, private, family, government, religion, education, medical, etc, etc. This way of understanding and ordering the world is a particularly Western (some might say Germanic) form.

Furthermore, there are languages that still survive to this day that have no word for "religion" as such, something I talk elsewhere in this thread. This says to me that in some cultures religion cannot even be conceived of as separate from culture because the language does not provide the imaginative capacity to understand it that way.

So, always fluid, yes. Separable, I don't know.