Its possible for two peole to have identical political positons while one
> labels him/herself "Marxist," the other uses the label "Christian."
>
To quote Max re: anarchism and Marxism above, "the categories are not quite distinct or opposing" (and even less so here, I would say). Christian Marxists aren't a particularly rare breed; the seminaries are full of 'em.
> If someone commits thenselves to the anti-capitalist struggle, what
> difference does it make what "ism" they classify their politics under?
Agreed. The most effective organizations to which I've belonged have been those that combined a broad range of people in a common struggle, regardless of their chosen label or lack thereof.
-- "Hige sceal þe heardra, heorte þe cenre, mod sceal þe mare, þe ure mægen lytlað."