What passages are there that address the issue of alcohol and drinking/drunkenness? How is it that wonderful Christian people who are undoubtedly devoted to Christ can disagree on whether Christians can or cannot drink alcohol?
I will answer your last question first. Why do so many Christians disagree on the subject of alcohol? I don't know all the reasons. For many, they have seen the detrimental effects of alcohol in themselves or their families, and want people to stay as far away from it as possible. Others who oppose any use of alcohol do so with the idea of "building a hedge around the scriptures," making sure people don't accidentally violate scripture by getting too close to the edge. Others honestly believe that Jesus and his followers never used alcohol, so we should not. On the other hand, some allow alcohol consumption because they want to justify themselves (hopefully a small number). Others believe that the scriptures clearly teach that Jesus and others consumed alcoholic wine. Most would agree that, whatever the Bible teaches about drinking, drunkenness is condemned.
I have recently seen an example of the conflict. I attended a congregation that taught that the "wine" used on the Passover was necessarily unfermented, so we can not use alcoholic wine in the Lord's Supper. I recently received an e-mail from a man who was arguing that there would not have been any unfermented wine at Passover, so we must use alcoholic wine in the Lord's Supper (even if it would set off a recovering alcoholic). There were definite problems with both their arguments, but it points out that many people go to the extremes on this issue. As with most other issues, the extremes are probably both wrong.
I am one of the roughly 33% of adults in the United States who do not drink alcohol. Many of those are recovering alcoholics, or fear that they are predisposed to becoming alcoholics. Others don't drink because of allergies, drug interactions, or simply a desire not to give up control of one's mind. Some are adamant that nobody should drink. Others say it is a personal choice. The Bible seems to take a neutral stance toward drinking, with a leaning toward abstinence. Drunkenness seems to be a scriptural "no-no."
Some of the passages that apply are:
Ephesians 5:18-19 - "Be not drunken with wine, wherein is riot, but be filled with the Spirit, speaking to one another in psalms, and hymns, and spiritual songs, singing and making melody in your heart to the Lord."
1 Timothy 3:3; Titus 1:7 (about elders) - "Not given to wine, no striker …"
1 Timothy 3:8 - "Deacons, in like manner, must be grave, not double-tongued, not given to much wine, not greedy of filthy lucre." (Note that it doesn't say not given to wine, but rather not to much wine.)
1 Timothy 5:23 - "Drink no longer water, but use a little wine for thy stomach's sake and thine often infirmities." (Both sides use this text. One says that the text says it's acceptable to drink wine in moderation. The other says, "See. Paul had to tell Timothy to take wine medicinally because he would not use it otherwise.")
Luke 7:33-34 - "For John the Baptist came neither eating bread nor drinking wine and ye say He hath a devil. The Son of Man came eating and drinking; and ye say, Behold a gluttonous man and a winebibber, a friend of publicans and sinners." (This indicates, perhaps, that Jesus was known for drinking alcoholic wine as opposed to John who would not even drink grape juice.)
John 2 - The turning of water into wine at a wedding feast in Cana. Again, both sides argue from this one, although the stronger argument seems to me to be that Jesus turned the water into alcoholic wine, not merely grape juice. Alcohol would be common at such a feast, and nobody would praise grape juice over the wine they had been drinking if it had no alcoholic content.)
Romans 14:21 - "It is good neither to eat flesh, nor to drink wine, nor any thing whereby they brother stumbleth, or is offended, or is made weak."
1 Peter 4:3-4 - "For the time past of our life may suffice us to have wrought the will of the Gentiles, when we walked in lasciviousness, lusts, excess of wine, revellings, banquetings, and abominable idolatires; wherein they think it strange that ye run not with them to the same excess of riot, speaking evil of you."
Proverbs 20:1 - "Wine is a mocker, strong drink is raging; and whosoever is deceived therby is not wise."
See also Proverbs 23:30-35, which accurately describes the drunkard.