because Christianity isn't about "don't do this, and don't do that". 1 Corinthians, 6:12 "All things are lawful for me, but not all things are profitable. All things are lawful for me, but I will not be mastered by anything."
Because when the religion was being written and edited by perfectly mortal and normal men (not women), beer was a staple food, a source of carbohydrates which was often consumed by the working class for breakfast. The relationship between alcohol and those consciously creating and editing the texts they wished to preserve for their own reasons, was one of utility. Alcohol was not seen to cause any problems, and in fact was useful to puff up the ego in warring soldiers and marketplace sellers and buyers. It also did not hurt to go against the jewish beliefs around this compound given that the religion was a kind of rebellion against judaism. Later on, Islam also had to take a stand against christianity, so it reversed that sentiment.
People, ancient and modern have always found it useful to change their consciousness by one method/substance or another. Be it mushrooms, peyote, Kava, fermentation,ect. No religion will ever stop the desire to seek permanent changes, that is-- , LSD-and other psychedelics--(probable), or temporary changes--alcohol. And frankly, the consumption of alcohol in this capitalist society is a perfect drug for all intents and purposes. Very good for the economy-hospitals to be used, cops to be involved, cars to be re-cycled or repaired, fines to be paid,etc. In other words, money is made ALL down the line by allowing alcohol indulgence by citizens. Colorado and Washington are just the first to recognize that folks are going to smoke the JUJU, whether authorities like it or not. Human nature, sin or otherwise.
If there is a god, it's not concerned with our choice of beverages. All abrahamic religions moral guidelines are about preserving the status quo. In the days before most people could read. I wouldn't worry too much about sins unless you don't have a moral compass that tells you that hurting people is wrong.
Well when you base a lot of your teachings on indo-euro mythology, you gotta allow for drinking. Just doesn't work otherwise.
Some muslims drink alcohol too but they drink it by knowing what they are doing is a sin. Conservative ones don't drink.
This is a guess, of course - The main utilites of christianity, in a lot of places, are those of control and exploitation (irregardless of the original philosophy of the person whose teachings inspired it). Why would people/governments who use christianity for exploitation try to cut out a major source of income/tax income, that only comes at the expense of others? It's not about salvation.