The word "Muslim" means "one who submits." Islam is a religion of submission to the will of Allah. The straightforward truth is that someone who is not in control of their own body because they are drunk can not submit to Allah's will, as they have not the control to make that choice. So Islam forbids alcohol primarily for that reason to prevent Shaytan (the Devil) taking control of a person's body when they are too intoxicated to control their body themselves. If that happened the person would not then subject to Allah's will, but rather they would then be a slave to sin. In the Qur'an it says: "Shaytan's plan is to excite enmity and hatred between you, with intoxicants and gambling, and hinder you from the remembrance of Allah, and from prayer: will ye not then abstain? (Surah 5:91) .......