...but evidence of warp worship is rather thin on the ground in their fluff.
Yeah, it's not like there's a novel with the antagonist being an Alpha Legion Daemon Prince. And the 3.5 C:CSM didn't state that while they needed Cultists to summon daemons, that they weren't eager to field daemons on the battlefield. Or that the Index Astartes article says the Legion employs mutated and Possessed Marines. Or the codices all have pictures of Legionnaires with horned helms and spiked greaves and clearly mutated bits & weapons.
But yeah, let's call that evidence "thin."
Voldorius was drek and can be safely considered an outlier given its take on AL had almost nothing in common with the lore proper, the 3.5 Codex doubles down on them not having the situation for daemonspam (ie: "too far from the Eye of Terror", "the bulk of the Legion stayed in real space") but being pragmatic enough to use them if necessary when cultists start summoning them, that the mutations were explicitly stated to be hidden out of pragmatism (and no mention of possessed if I recall correctly), and that horns/spikes are pretty generic visuals- actually, on that note, mutated weapons don't really appear in AL artwork. Never mind that intentionally confusing visuals are a major canonical character trait for the Legion, which is its own can of worms.
"While the Alpha legion does not reside in the Eye of Terror, and therefore is not plagued by the Warping effects of that maelstrom of insanity, there is still evidence of mutation in the gene-seed. If this was the case prior to the Heresy, it was kept concealed, but given the legion's predilection for secrecy that would not be surprising. During the Lethe Ambush, mutated Alpha Legion Space Marines hid their warped body parts, not out of shame, but so they could reveal them as they attacked - adding horror and revulsion to the shock of their sudden attack."
Note that this Index Astartes is framed as being untrustworthy AL propaganda in-universe, which just muddies the waters further.
If that evidence is meant to be warp worship rather than simply heretical willingness to use tools, then Eisenhorn's a devout Chaos worshiper and so's every other Radical Inquisitor.
Edited by Lucerne, 23 January 2020 - 06:49 PM.