The phrase "homogenous entity" is correct and usable in written English.
It can be used when describing a group or collection of things that are all the same or similar in some way. Example: "The company's marketing strategy aims to target a homogenous entity of young, tech-savvy consumers."
By its nature it is not an homogenous entity.
The Kremlin is by no means a homogenous entity.
This from Reuters: "European bond markets are no longer a homogenous entity, which has reduced their attractiveness to foreign investors," strategists at BNP wrote in a note.
But I wonder whether the Sun realises that its message is similar: the effect of treating Muslims, all Muslims, as some kind of homogenous entity (and as a thing apart) is more likely to foment divisions with non-Muslims and alienate Muslims still further.
However, security is not a homogenous entity either.
Unipolar depression is not a uniform, homogenous entity.
For a group that says it's focused on encouraging diversity, Accord talks about faith schools as homogenous entities.
After half a century of labour immigration, even the European peoples, given their growing ethnic, linguistic, and religious pluralism, can no longer be conceived as culturally homogenous entities.
Fine roots (⩽2 mm in diameter) of tree species, traditionally regarded as homogenous entities, are expected to be major contributors of forest soil organic carbon (C), but their contributions need to be reevaluated given the heterogeneity in many root characteristics within fine-root architecture.
Our results demonstrate that, as expected, dog breeds do not constitute homogenous entities and population stratification needs to be systematically assessed in association studies.
Consequently, many of the tuberculin fractions previously described as homogenous entities actually consist of multiple mycobacterial proteins.
