Why is religion not separated from the state, considering man's opinion as the criterion, as in the West?

The western experience came as a reaction to the dominance and alliance between the church and the state, by dominating people's properties and minds during the middle ages. However, the Islamic world has never faced such a problem due to the practicality and rationality of the Islamic system.

As a matter of fact, we need an established divine legislation that suits man in all conditions. We do not need resources that depend on man's personal whims, desires, and on mood swings, as is the situation with the legalization of usury, homosexuality and others. We do not also need references written down by the strong to be a burden on the weak as in capitalism, or communism that contradicts man's natural desire for ownership.