Why drinking alcohol in Islam is a sin?

Answer

Drinking alcohol is a sin because it is forbidden by God and his prophet Mohamed (peace upon him). Quran says (in meaning translation):

" O you who believe! Intoxicants (all kinds of alcoholic drinks) and gambling..... are an abomination of Satan handiwork. so, avoid (strictly all) that abomination in order that you may be successful. Satan wants only to excite enmity and hatred between you with intoxicants (alcoholic drinks) and gambling, and hinder you from the remembrance of ALLAH (God) and from the prayer. So, will you not then abstain"

[Quran, chapter 5, verse 90-91].

On the other hand, there is no health benefit of drinking alcohols but it is waste of money. Drinking alcohol has many negative health effect.

Drinking alcohol is also sinful in all religions including Judaism and Christanity although some Christian denominations do not forbid alchohol drinking.

Excellent answer above. I'll add that drinking does heavy damage to one's liver and nervous system. It causes alcohol addiction and impairs the senses. It is one of the main causes behind car accidents. For pregnant women, alcohol can handicap the baby. It is also, of course, a big waste of money. Drinking can also lead to rape, robbery, and other crimes that wouldn't be done while sober.

There is wisdom in forbidding alcohol.

Yes, it is very sinful. Allah does not want us to harm our bodies by drinking Alchol. And when you drink Alchol you are not in control in your actions.All drugs that arent good for your body is sinful.