When did Emperor worship become the norm?

[Denzark]

Here's something my fluff-fu isn't up to speed on - namely, when did worshipping the Emperor become sanctioned/compulsory/the norm?

Reading the HH books, and obviously the Emperor has put a hold on all religions. Now, at some point he fights Horus, is lively enough (still able to speak) to give Dorn instructions for the Golden Throne, where after a while he becomes less and less able to speak and then becomes the living corpse we all know and love. So, who declares him divine, and why?

Was it himself? Because he needed to harness the worship of his people to fight on?

Did the ecclesiarchy/high lords wait until he was unable to fight against this notion, and what for - did they think he would be a puppet God?

I've seen how the ecclesiarchy came about - but what I am trying to dig into was why, when, and what for, did the immortal Emperor finally allow worship of himself as a deity?

[Old_Paladin]

Worship started before he was even in the golden throne; he just tried to put a stop to it whenever it became too common or affected peoples attitudes or actions.

As soon as he was actually in the throne, people would have reverted towards those beliefs pretty quickly.
It also would have been a very valuable tool post heresy, in order to maintain control and calm fears during a time of potential renewed rebellion.

[Pendragon38]

Sounds like you need to look in are past for the answer: Roman Times,like Constantine The Great lay on his death bed Baptized as a Christan ....and blame 300 and so years later they become more powerful than any Faction in the old World.2,000years later still here

[jorz192]

In the Horus Heresy books many times it is mentioned about the undercurrents of
illegal worship of the emperor. The worship of the Emperor developed after his
placement in the golden throne.

Ten thousand years have passed since the Horus heresy and it is conceivable that
the cult of the emperor developed reasonably slowly.

[imperialsavant]

The belief in the Emperors Divinity was already widespread albeit in an "underground" way via the Lectitio Divinitatus which was passed around by human members of the Great Crusade. You can read reference to it in "Galaxy in Flames" & 'the Flight of the Eisenstein".
It continued to spread at a much greater rate during & particularly after the Horus Heresy.

[Vaddok Sek]

Here you go
http://wh40k.lexicanum.com/wiki/Ecclesiarchy#History