Baptism is a Christian ritual that involves washing water over the head or entire body of someone who is publicly entering the church. Whether the baptism is done by dunking someone entirely under the water (a practice common among Baptists) or sprinkling water on someone's forehead (a practice common in the Roman Catholic Church), water is important because of its presence in the baptism of Jesus and because of its symbolic qualities.
The ritual is rooted in the practices of John the Baptist who used baptism as a way to help people seek forgiveness from their sins (Matthew 3:1-12, Luke 3:1-14) and in Jesus' own baptism at the hands of John the Baptist (Matthew 3:13-17, Mark 1:9-11, Luke 3:15-17). The church continues the practice not only in imitation of Jesus' life and ministry, but also in fulfillment of Jesus' final command in Matthew 28:18-20 to "[g]o therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you; and lo, I am with you always, to the end of the age." Baptisms are almost exclusively performed by ordained clergy. Although the details of a baptism vary a lot across denominations, the clergy will somehow put water upon the person's head (by sprinkling, pouring, etc.) or whole body (by dunking). The vast majority of clergy will then say, "I baptize you in the name of the Father and of the Son and of the Holy Spirit." While baptizing in the name of the Trinity is the most common and most historically practiced method, some denominations baptize "in the name of Jesus," and some pastors baptize in the name of the "Creator, Sustainer, Redeemer" or other alternative formulas. After baptizing a person or group of people, the congregation will then make a pledge to welcome the baptized into their community and help that person grow in his or her faith.
Baptism is an important part of Christian life. It is considered a sacrament in all churches that have sacraments, and is therefore a "means of grace," or process through which God's grace is given to a person. In some churches, only adults or persons considered old enough to make decisions for themselves (usually this means that they must be an adolescent) are eligible for baptism because it is a life-long commitment to live a Christ-like life and be a part of the church. In their tradition, baptism is something that should be remembered and understood before it is done. Adult baptism is most common in what are generally considered to be "conservative" or "evangelical" traditions, such as Baptists, Church of God, or Pentecostal. In other churches, infants may be baptized as well as adults. In these traditions, baptism is understood to be a life-long commitment to live a Christ-like life and to be a part of the church; however, they feel that this is a promise that a parent can make on behalf of a child. In these traditions, which tend to be considered "liberal," "mainline," or "sacramental," a person is given the chance later in life to go through a process called "confirmation" in which they confirm the vows made for them at their baptism. Churches that do not baptize infants will generally have a "commissioning service" in which the baby is presented to a congregation who then promise to raise the child in the faith.
Christians draw meaning from the properties in water as they understand baptism. Water is used to wash- similarly, baptism is understood as a cleansing of one's soul from the marks of sin. Water is life-giving- similarly, baptism is understood to be a life-giving ritual. Through baptism, people are permanently brought into the community of faith that will help them lead a more fulfilling life. Water is also dangerous, and people cannot breathe under water. Because of this, in Scripture (i.e., Rom. 6) and the church tradition, baptism is seen as a death with an immediate new life. Baptism, therefore, is an enormous commitment. Through baptism, a person loses her or his own life, and the life then belongs to God and the church.