They all have certain core beliefs in common, the main two being the blind worship of something (The State, Galia or Allah) and the desire to suppress all freedom of thought to keep the "lower classes" in their place.
This un-holy trinity of Marxist, Jihadist and Eco-nuts is an odd grouping to be sure. But no stranger then the Axis of Germany, Japan and Italy. Firm allies despite two of them being convinced that they were the master race.