All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad is His slave and Messenger.
Drinking alcohol does not lead to disbelief (i.e. does not take a person out of the fold of Islam), but it is one of the grave major sins; one must avoid it and stay far away from it, as Allaah says (what means): {O you who have believed, indeed, intoxicants, gambling, [sacrificing on] stone altars [to other than Allaah], and divining arrows are but defilement from the work of Satan, so avoid it that you may be successful. Satan only wants to cause between you animosity and hatred through intoxicants and gambling and to avert you from the remembrance of Allaah and from prayer. So will you not desist?} [Quran 5:90-91]
The hadd (corporal punishment) is not applied on a person who has consumed alcohol unless this is proven by his confession or by the testimony of two witnesses.
There is a difference of opinion regarding punishing him based on an indication such as smelling the odor of alcohol from him.
Shaykh Ibn Taymiyyah said:
“It is an obligation to apply the hadd on him if there is evidence or if the drinker confessed to it. If the smell of alcohol is found from him, or he was seen vomiting it, then it was said that the hadd is not applied on him, as it is probable that what he drank was not alcohol, that he drank it while he was ignorant of the fact that it was alcohol, or that he was forced to drink it, and so on. It was also said, 'He is to be lashed if he knew that it was an intoxicant.' This is what was reported from the rightly-guided Caliphs and other Companions such as Caliphs ‘Uthmaan and ‘Ali, and Ibn Mas’ood . The Sunnah of the Prophet also proves this, and this is what the people agreed upon. It is also the view of Maalik and Ahmad in most of his texts, and others.”
Ibn Qudaamah said in al-Mughni:
“According to the view of most scholars; among whom are Ath-Thawri, Abu Haneefah, and Ash-Shaafi', it is not an obligation to apply the hadd on him because of the presence of the smell of alcohol in his mouth. However, Abu Taalib narrated from Ahmad that he is lashed due to that. This is the view of Maalik because Ibn Mas’ood applied the hadd on a man on whom he found the smell of alcohol. Also, it was reported that 'Umar said, 'I found the smell of alcohol in 'Ubaydullaah, and he confessed that he drank at-tilaa' (a kind of wine). 'Umar said, 'I will ask about it, if it is intoxicating, then I will apply the hadd on him.' This is because the smell indicates that he had drunk it, so the smell is considered as confessing. The first view is more appropriate because it is probable that he has only rinsed his mouth with it; or that he thought that it was water and spitted it out; or that he thought that it does not intoxicate; or that he was under compulsion; or that he ate fermented berries; or that he drank apple cider, which smells like alcohol. Since all this is probable, then lashing him is not obligatory if it is removed by doubtfulness. The hadeeth of ‘Umar is evidence for us as he did not apply the hadd on that man just because he found a smell from him, because if it was an obligation to apply the hadd on him, then ‘Umar would have hastened to apply it, and Allaah knows best.”
In case the hadd is not applied on the drinker of alcohol, and he did not repent, then he would be under the Will of Allaah; Allaah may punish him, or may forgive him; Allaah says (what means): {Indeed, Allaah does not forgive association with Him, but He forgives what is less than that for whom He wills.} [Quran 4:48]
Among the evidence of his punishment in the Hereafter is the hadeeth in which the Prophet said, “Every intoxicant is forbidden. Verily, Allaah vowed that those who drank intoxicants will drink from the river of Khabaal.” The Prophet was asked, “And what is the river of Khabaal?” He replied, “The pus or sweat of the people of the Hellfire.” [Muslim]
Moreover, ‘Abdullaah ibn ‘Amr said, “Whoever drinks wine in this worldly life and does not repent from it will be forbidden from drinking it in the Hereafter.” [Al-Bukhari and Muslim]
The narration by Muslim reads, “Whoever drinks alcohol in this worldly life and dies while addicted to it and without repenting from it will not drink it in the Hereafter.”
Allaah knows best.