Teetotalism is the practice of complete abstinence from alcoholic beverages. Anyone who practices teetotalism is called a teetotaler. The phrase comes from an emphasis on the "T" in "total abstinence".
Although the Bible does not completely forbid the consumption of alcohol by believers, it has many warnings against its use. As such, many Christian churches and denominations forbid its use by members or at least strongly urge its members not to partake (at the minimum, the church leadership -- pastors, elders, and deacons -- may be required to be teetotalers). The Baptist denominations are the most notable adherents to teetotalism, to the point where in the Lord's Supper grape juice is used instead of wine.