Why did Allah prohibit the drinking of wine to believers?
According to the Yezidis, it was out of jealousy and fear.
Islamic law generally prohibits the use of intoxicants to Muslims—not that this has slowed the use of drugs such as qat and hashish in the Muslim world, mind you—and Wine is regarded as the first, the chief, the Mother of all Intoxicants.
(When coffee was first discovered, Muslim religious authorities ruled it an intoxicant, and its use therefore forbidden to Muslims. This ruling was so universally rejected by the 'umma that in the end the mullahs just had to suck it up.)
Known euphemistically in Arabic as the Red One—as if even to pronounce its name would be dangerous—wine is specifically forbidden in the Qur'an. Though the book itself provides no reasons for this prohibition, the Yezidis—a Kurdish-speaking religious minority centered in Iraq, whose worship of the Peacock Angel would seem to have arisen in the 13th century in antinomian protest against the tyranny of the Mosque—do.
(That, in Europe, what we now know as Old Craft also arose in antinomian protest against a tyrannical Church, at roughly the same time, must be considered, at very least, a striking coincidence, if not the actual Hand of some god.
Presumably, the Left Hand.)
When Allah saw how much humanity loved the Red One, they say, he feared that they would always love and worship it more than himself.
Therefore, in jealousy, he did what those unequal to the race—just as Republicans in the US are trying to do today—always do.
He banned the competition.
(That Islamic mystical tradition has always equated Wine with Divine Love tells a truth both older and deeper than any Revelation.)
The blood of the grape is the blood of a god, Red Blood of a Green God. Before any others, the Green Man first wore vine leaves.
(This, by the way, is historically true. The icon of modern paganism known as the Green Man, Leaf Mask, or Foliate Head first arose about 2000 years ago, directly out of Dionysiac art.)
Now, as ever since the Elder Days, the Plant-Lord feeds us with His flesh, and makes us giddy (< Old English gydig, literally “god-y”, i.e. “filled with a god”) with His blood.
“When all the other gods let you down,” says an old Roman proverb, “there's always Bacchus.”