An early Bronze age / Iron age agricultural society , the coming of winter posses real problems……by midwinter it is obvious that there will not be enough stored fodder to keep the herds/flocks fed ,fit and well until the spring. So.. what to do ?

Solution … Select the weakest of the flock for slaughter …

Cull half the flock , thus ensuring the remaining half has enough fodder to survive until the spring …when the numbers can be bred up again. Now the problem becomes what to do with all the meat ,(the hides ,skins ,horns ,fleeces etc. all become useful products).

But all that meat…. Imperfect storage technology/facilities…..solution large midwinter feast…(spread the wealth ,reinforce societies bonds ,help the family/clan/tribe survive the winter).

So…really big party lots of food…lots of drink….clans meet up for socialising…arranging betrothals /weddings…trading land /goods etc.

Check out History and cultural significance below…

https://en.wikipedia.org/wiki/Winter_solstice

Now along comes a new ,somewhat austere religion , trying to ban such gatherings….. not unsurprisingly the population objects …. And of course ,whatever the religion.. the core reason for the feasts remains the same…agricultural necessity .

So unable to ban the jollity the religion simply overwrites its own myths onto the society. Done once it becomes increasingly easy to repeat the exercise with all “suspect” celebrations….. Samain becomes All Hallows eve……Imbolg becomes Candlemas….. Beltane becomes Ascension Day ….. Eostre becomes Easter etc.etc.
Initially the participants notice no changes… then slowly the old pagan motifs are “discouraged” and over time become forgotten ….
then over years ,decades ,centuries…..
why the religion has always been there….
ALWAYS….

UNDERSTAND ???

OR ELSE !