Although Althusser was a very important member of the PCF, and admittedly one of his last international stature intellectual, his great "project" on Marxism (project is understood here in its sense so decisive for Bachelard him), namely among others, that what was written by Marx does not necessarily fall within the Marxism, this ambition seems, time helping, have turned against its creator. This could be the "verdict" historical fact in the work of Althusser, an irony that wanted to just update the Continent-history inaugurated by Marx.
In short, Althusser questioned in Marxist ... but he has never been able to respond in a Marxist.