The empire doesnt actually need to enforce the Talos ban. The Thalmor will attack when they are ready, not a day sooner or later than that. Worship of Talos wont make them attack sooner, and banning it wont delay it. So what is the empire's real motive for Talos banning?

the empire is really jsut a group of boot-licking push overs, the idiots gave up when they should have kept on fighting (honestly they will not survive anotehr attack by the thalmor), they accepted horrible terms for their giving up and they cant even keep a hold on their provinces

They didn't, until Ulfric Stormcloak started jumping up and down shouting "hey look at me I'm worshipping Talos"

I don't think they've ever quite banned it. It seems like they like looked the other way and didn't quite take it as seriously, for a good 30 years. Some Nords in game say people still worshipped Talos, but not publicly. It came to head in the Markarth incident, when Ulfric wanted the whole city to public oust the ruling. Someone can correct me if I'm wrong, but that's what I've gathered. Suddenly that alarmed the Thalmor to deliver on their threats, and the empire is caught between both -- leaning towards letting the Thalmor do what they want, of course. But I don't think they ever care to enforce the rules themselves.

The Empire did not enforce it until Ulfric made a deal with the Jarl of Markarth (the current one's father I think). The deal was that Ulfric and his men could openly worship Talos in exchange for helping to erradicate the Forsworn presence within the city. The Thalmor got wind of this, told the Empire to hold up their end of the deal, and the rest is history.

Honestly, I think the Thalmor are more powerful than the Empire NOW, but during the Great War, I think the Empire should have held out to the bloody end. It was a stalemate, but "Emperor" Mede signed the WGC, basically giving the win to the Thalmor. The Empire has no idea how powerful the Thalmor are, so they are fooling themselves by saying the Thalmor don't want to destroy Man and are not building up their forces to strike.

It gives them the option to at least stall the Thalmor when they want to have Thalmor agents go somewhere and "investigate Talos worship". Which really, could be quite useful if they do in fact have secret weapons for use in the upcoming war. They can also allow open Talos worship in certain places to distract the Thalmor, as misdirection and intentional provocation to further conflict. Religious fanatics are actually quite easy to manipulate, given such leverage.
What, you think just because you are the dragonborn, you know all of the Empire's plans? Taking a blow in order to draw the enemy in is not only an old trick, its one that is well documented in the game lore.

bingo, most people seem to forget, or ignore, this fact when arguing aganst the stormcloaks for some reason

So the empire naively think banning Talos will prevent the Thalmor from attacking?

Not just that.. but I think they have such a political mindset and need for trying to unite with people, that they end up selling themselves out in order to try to make a space for the Thalmor. They simply don't realize that it's destined for war, that one or the other has to go. Integrating with them is impossible.

edit: I still think that even if you side with them, you'd probably take up much of the Stormclock cause anyways. I don't think siding with the empire means further siding with the Thalmor. They know at this point war is coming too.

From talking to General Tulios, its pretty clear that no, they expect another war, and just want to buy time to get ready.

As Korr notes, the empire did not actively persecute Talos worshippers. Also, being imperials they (i) didn't case as much about Talos, and (ii) assumed that those who did would simply keep quiet about it. But Ulfric was too proud to do so, or allow his people to do so. Whereas at least one other (prominent) character in the game does worship Talos in secret.

This. Ulfric either doesn't realize this (which I find unlikely) or doesn't care, but I don't think the Nords can beat the Thalmor by themselves.

the thalmor need to be destroyed

But the idea that they are buying time is a false one. The Thalmor arent ready to attack just yet, and as soon as they are ready, they will. How could Tullius know that war is coming but not know this? It doesnt make sense.

I've heard similar claims. Are there any evindence to back up the claim that the Thalmor are trying to destroy Men?

No, that would be quite stupid. However, they did hope that signing a peace treaty with the Thalmor would give them time to rebuild their army before the next war. However, their diplomats must have been quite inept as they allowed the Thalmor to get a number of concessions, one among them were the banning of Talos worship. Which set the stage for the Civil War. The Thalmor diplomats, on the other hand, must be quite skilled.

The Empire is buying time, not the Thalmor. Or am I not understanding what you're saying?

The claim is that the empire is buying time. Im saying they arent. The Thalmor WILL attack as soon as they are ready. Banning Talos wont delay that, and allowing Talos worship wont hasten it.

Basically, the empire is a bunch of snivelling simpleton politicians who falsely believe that signing a 'peace' agreement with a enemy that is dedicated to destroying the world will actually protect them. They basically agreed to allow the Thalmor to operate openly throughout their sovereign territory abducting and killing imperial citizens at will.

Anyone that would agree to any such terms just to broker a false 'peace' contract is a poor and unworthy leader. The stormcloaks had every right to rebel against an empire that no longer serves their interests.

Yeah the Thalmor are pretty powerful and I say stronger then the Empire now. They have taken over basically more then a few provinces by making backhanded deals with the other races. I will bet they will be the new empire by the time TES 6 comes out. Unless someone like the Dragonborn or whomever tries to stop their takeover before that.

The real question is why do the Thalmor insist on the Empire banning Talos worship, when if they simply let it go, the treaty would be much less obnoxious to most of the Empire. What's so important that they insist on this one stipulation, which has no obvious military effect, as if it were the most important part of the treaty?

There's an answer to the question, but it gets spoilery - which means it doesn't belong in this forum.

To spark a civil war, weakening the empire and forces in Skyrim

The empire accepted because they are weak, 'a shadow of their former self' says Ulfric.

There won't be a TES 6 if the Thalmor win.

They intend to unmake reality. http://www.imperial-library.info/content/forum-archives-michael-kirkbride

Do you think Ancano in the College quest line was just a lone looney with an omnicidal maniac bent? No. He saw the Eye of Magnus as a shortcut to the Thalmor's ultimate goal of unmaking the Mundus.

For all those saying that the Thalmor will attack "when they're ready", what if the Empire gets ready first? Men have a quicker rate of reproduction than elves. An entire generation has already passed since the end of the war.

Of course, the Thalmor probably haven't fully appreciated the walking threat to and refutation of their goals that was recently introduced to the equation... I doubt that the Dragonborn was inserted into the Mundus just to deal with the Alduin problem.

The empire nearly fell when the Dominion came knocking on Cyrodiil's door.
So they surrendered for self preservation, now the Thalmor hold sway. And the Thalmor are of course crushing the worship of Talos.

In Skyrim it's very obvious that no one's really thrown it away by anyone, the Empire or no one.. But it's just not openly and in official ways.
But if they start disregarding that the Thalmor smacked them around for a few years then.. The Thalmor will be back, and there is no way Cyrodiil is surviving it.

I like this! However, during the Diplomatic Immunity questline, the thalmor dossier about Esbern states http://www.imperial-library.info/content/thalmor-dossier-esbern
Unless the Thalmor sent to persecute Talos worshipers aren't privy to such information. If this is all true, I don't think the Thalmor were anticipating the Dragonborn, which could be why the Dark Brotherhood are sent to kill the dragonborn during gameplay. But, I don't know, if there is to be a TES 6, then events and info will become clearer, hopefully, and I can wait (though reluctantly and impatiently)!

There is no evidence in-game evidence The Thalmor want anything more then domination. I'm not going to take a post from the lore section of the forums made long before skyrim was released and apply it to the Thalmor without collaberating evidence. So much lore in the elderscrolls is conflicting.(just like History in real life). It could just as easily be the rantings of a fanatic who has no idea what holds the world together. (and from the sound of it he doesn't)

Even if the supposed plan of the Thalmor was true preserving the Kingdoms of Humanity is more important then the open worship of Talos. The Imperial army was devetated by the great war. The entire Great War was a defensive operation on the part of the Empire. They never had the opportunity to strike at the Dominion. At no point has anyone, Imperial, Nord or Redguard been able to take the fight to the Dominion. The choice was peace or defeat. At no point in the war was the Empire able to attack Valenwood or the Summerset Isles. The Empire needs time to rebuild its armies and perhaps attack the Summerset Isles on its own terms. I'd try to reestablish ties with the Argonians of Blackmarsh. Because an army that can swim really well and breath underwater are quite useful when assaulting an island.