I am 15 years old. Is it a sin to drink wine, champagne or beer? I'm going for a party next week and there might be drinks. Is it a sin in to drink them?
In most countries around the world the minimum allowable age to drink alcohol is 18 (some countries, such as the United States have a minimum age of 21). The reason is that alcohol is addictive and teenage brains are particularly susceptible during development. Alcohol also can cause damage which again more likely to happen in a developing brain.
God tells us to obey the laws of our government. "Let every soul be subject to the governing authorities. For there is no authority except from God, and the authorities that exist are appointed by God. Therefore whoever resists the authority resists the ordinance of God, and those who resist will bring judgment on themselves" (Romans 13:1-2).
For Christians, there are even more reasons not to drink. We are commanded to be sober at all times. "You are all sons of light and sons of the day. We are not of the night nor of darkness. Therefore let us not sleep, as others do, but let us watch and be sober" (I Thessalonians 5:5-6). For more on this topic, see Old Testament Beverages and New Testament Beverages.