Idpol is not something you can properly define because it is often contextual to the situation - its placing the onus on identity rather than material conditions within certain contexts. Its inverse of course is the idea of "class reductionism" - something that only exists conceptually a lot of the time but there does exist a number of vulgar marxists who attempt to use it.
So for example, lets say gay people. As an example, gay people in the US have had discrimination in the job market for a long time, and still does in many places in the US. The material reason for why is of course that the social beliefs of the US bouj precluded gay people from being accepted within society because their cultural beliefs are downstream of the psuedo-christian Protestantism that is the progenitor of modern US culture.
Of course the idpol understanding of this scenario might be>gay people don't get the jobs because they are lazy bums who enjoy looking at their co-worker's asses more than actually working
and the class reductionist understanding might be<gay people have less representation in the workforce because they are part of the petite-bourgeoisie
Usually, class reductionist narratives like this tend to rely on their own cultural preconceptions in the same way that idpol does - just, with a vulgar materialist lingo applied. Cuba was for a time one such country where homosexuality was believed to be a bourgeois decadence - an artificial lifestyle developed out of the conditions of capitalist living, until further research and social sciencing in Cuba proved it to be wrong, to which Castro backtracked the policy of imprisoning homosexuals and shifted the country towards LGBTQ+ acceptance.
This example also shows that the proper materialist line is not always a purely material one - as was said by Marx and further codified by Lenin, society exists with its material base and social superstructure, and both influence each other. While it is tempting to believe solely in the material base of things, social discrimination and stratification inevitably do lead to material consequences, and as such social conditions have to be considered within a materialist perspective. Has a certain social bias elevated or lowered a group of people in the material hierarchy of things? A good example of this is apartheid states like Israel or South Africa, where social restrictions on Palestinians/blacks lead to losses of material opportunities and capacity which made them a poor underclass to be exploited by their apartheid masters. In most all capitalist countries you can usually find at least one but usually a group of people who are socially disadvantaged which has lead to their material subjugation as an underclass.
As such, it is not necessarily idpol to have considerations for people's social characteristics, as long as you can reasonably prove those social characteristics have lead to differing forms of material inequality. As was said by Engles himself:Marx and I are ourselves partly to blame for the fact that the younger people sometimes lay more stress on the economic side than is due to it. We had to emphasise the main principle vis-à-vis our adversaries, who denied it, and we had not always the time, the place or the opportunity to give their due to the other elements involved in the interaction. But when it came to presenting a section of history, that is, to making a practical application, it was a different matter and there no error was permissible. Unfortunately, however, it happens only too often that people think they have fully understood a new theory and can apply it without more ado from the moment they have assimilated its main principles, and even those not always correctly. And I cannot exempt many of the more recent "Marxists" from this reproach, for the most amazing rubbish has been produced in this quarter, too….https://www.marxists.org/archive/marx/works/1890/letters/90_09_21.htm
Since idpol and "class reductionism" are so functionally similar, I will consolidate them to talk about this last bit. Idpol exists in a few different manifestations rather than just being one form of expression, it is used in different ways to dull consciousness and sew dissent and division between the proletariat.
It can manifest as:Systematic
, where it is used as a mode of characterization of a people to either ascribe intrinsic qualities to them or excuse facts of that group by virtue of a shared identity. Systematic idpol is often used by political groups of government organizations to demonize or lionize different identity groups to suit their political agendas, and often to carry out some material agenda to subjugate certain peoples as an underclass and sometimes marginally materially elevate their political base by said labor. Apartheid states are a very easy to understand example of this.Interpersonal
, where idpol identities are used to characterize interactions between people - usually made as a way to have other people express deference or loathing towards a certain identity group through ingrained social actions. This is usually more a personalized form of expression of systematic idpol, but it can exist independent from it, a good example being tumblerinas which expect undue social deference being given towards minority groups because of their oppression - sometimes called "the progressive stack".Hierarchical
, where identities promote certain social hierarchies based on socially held ranks of said identities. Again, usually co-dependent on systematic idpol but can exist independent of it. A good example of this is """race sciences""" which promote a certain hierarchy of humanity, usually justified on the basis of "inherent intelligence" of a given race structured so that the supposed "smartest races" are put above the "dumbest races".
All of these expressions of idpol can exist concurrently and co-dependently of one another, but also independently of each other, depending on the social structures. Most regimes which enforce an idpol agenda, however, tend to utilize all 3 to make sure that idpol is cemented in all layers of life - social, material, interpersonal, ect. Understanding these different expressions of idpol is important because they all are meant to divide the proletariat between different angles, and often it is so immersed within the societal experience of proles that they can hold these expressions without even realizing what it is. Each different form of expression has to be fought in different ways, often contextually dependent on what idpols it is trying to promote as well. This is where there can't be any one-size-fits-all anti-idpol approach, but rather well-honed instincts and material analysis which dissects the nature of how idpol is being used to divide the proletariat and how that idpol is unjustly affecting other proles.