I have read some of the Horus heresy books, and was wondering this, can we win this or is their really only a almost never ending war in the future?​

*************POSSIBLE SPOILERS**************​

• The Emperor sits on his throne (a life support device)
• His life support is a thousand psychers a day that are deemed ineffective, they are sacrificed so that their energy can keep him alive.
• He is using all his energy to keep the demons form the web-way magnus broke behind the throne.
• He is kept to busy to really help the rest of the imperium, besides the fact he keeps the capitol safe from demon.
• Chaos is only getting stronger as more psychic energy is used.
• The orks and Eldar lead to the creation of the chaos gods through the psychic races stirring the warp.
• The emeperors throne is also a huge psychic beacon.
• ^^^^ It draws the demons in and it also calls to the hive mind of the Great Devourer. Tyranids are being draw from the outside in.

_______please critique my information to help keep things straight and also please answer my poll.

To be honest, playing advocate of Malal here. (He's still Chaos, right?) I voted that the Imperium of Man can defeat Chaos; pre-heresy he came close to it, by creating the Golden Throne as a means to create a human-webway.
Magnus the Red ruined it to warn the Emperor of Horus by using sorcery and thus destroying the machinery at the location. It is now used as a life-support, but it can be mended; perhaps only by the Emperor.

Let's tap into another theory; the Emperor dies, it is likely that he will be reincarnated as a true God, especially after rumours of the true children and the illuminati hint in the way that the death of the Emperor will cause an eruption of Order in the Maelstrom; as a human-being he was already feared by the almighty Chaos Gods.
What if he is to become an immaterial God who guides mankind. As for now, he is imprisoned in his own rotting corpse.

Last; Chaos does not want to win and completely be victorious. It is Chaos, it is custard falling from the sky; sometimes they win, sometimes they lose; even bits of order is inevitable. The only enemy to Chaos is stagnation; as long as there is change, Chaos endures. If Chaos defeats the Empire of Man completely they will likely create another circle of destruction and carnage; they need their "opposites" of Order as well. As long as there's psychic presence, Chaos in some form or another will continue. Chaos is both an underdog and the ultimate champion.
I sound confusing, but it all makes sense. Chaos is so complex and yet so simplistic?

Yet, the question is: can they beat Chaos. Of course, there's endless possibilities that there might even be several paths. Does it truly be that they beat Chaos; that remains a question only Tzeentch can likely answer.

The main issue here is the Imperiums trump-card. Namely the reincarnation or "awakening" of The Emperor. We still have no idea if he's in any position to truly destroy the entities in the Warp even at the height of his power.

As it's been plainly stated; As long there's emotion in the galaxy, sentient life - Chaos will exist. Perhaps in a calmer state than in the 41st millenium. But it will never simply disappear.

The problem with Chaos is that it feeds off emotions. So for as long as there are mortals with feelings, they will linger in some form - even if the Gods of Chaos are reduced to non-sentient level.

The only way to REALLY ward off the Warp would be to seal the barriers between realspace and the Immaterium forever (which the Oldcrons were trying to do, unsure about the Newcrons) but that would have dire consequences for most races.

So the only way to get rid of Chaos for an eternity is for the entire galaxy to be ruled with Necrons or other beings who lack emotions.

Or, preferably, glorious Eldar master race who can constrain their own emotions thus denying She Who Thirsts power.

For this fight I was excluding all other armies and races that were fighting the Imperium and the same with Chaos and thought of both powers just going for each other, and my answer is no with a but..

The IoM would have enough power to snuff out all but the most underground and hidden chaos cults and shoot down any warband that thinks it's cool enough to enter back into reality, sadly the IoM without the Emperor have no hope in dealing with the Chaos gods themselves so they will live and they will still thrive, deamon invasions will happen but wont be able to do much both would be in the same position. Chaos could try and invade reality but will be shot down quickly and the IoM can launch foolish crusades right into the eye but those are just as doomed to fail.

Well I find Chaos as an ever living thing that feeds off of others. Plus I'm pretty sure that the Golden Throne is suppose to malfunction sooner or later from the age (thank you Nurgle) and so the Emperor is then to "Officially" by some (not me ) die then. Plus even if the Chaos Space Marines are defeated, the demons will still continue because they don't die in the material universe they are just sent back to the warp to be called upon again.

Honestly after reading the Chaos Demon Codex and all their history (well haven't read the WHOLE thing but all the God's and their realms/demons etc.) I really don't think that any race can stand up to Chaos, it says that even the Tyranids avoid Warp Storms and Demon Incursions, thus implying they either fear Demons or know they are outmatched either way one of the most powerful Xenos races cannot even with all it's might stand up to the power of the Dark Gods. And another thing even if all the other races/factions were destroyed except for the Eldar and Demons, then there are still technically the "Dark Eldar" that still feel emotions therefore powering Slaanesh and also probably the other Gods as well (Since Dark Eldar society is pretty f$%&*d). But that's only my opinion and I really don't see any way anyone can stand against the combined might of the Chaos Space Marines AND Chaos Demons.

Tyranids probably avoid daemon forces because fighting them is pointless.

The Tyranids sole goal is to expand and harvest biomass, but you can't harvest biomass from a daemon force.

Ehh, when reading the Demon Codex that's not how it seemed but oh well, either way they avoid Demons.