The act of baptism as a rite of initiation into the Christian faith is understood differently from one part of the Christian family to another. To most mainline Protestant denominations, as well as those of the Roman Catholic faith, baptism is a rite that is done one time in a person's life. It is not to be repeated because it is seen as a work of God (a sacrament) which does not need to be done again because God's promises to us revealed through our baptism as sure and permanent for our entire lives. Churches that practice infant baptism, which is done in most mainline denominations and in the Roman Catholic Church, usually link baptism to confirmation which is the teaching of the faith and accepting of baptismal vows by a person when that person becomes a young adult. In this way, the vows made by parents at the baptism of an infant are confirmed by that infant when he/she has reached an age to understand what the promises made on his/her behalf really meant.
In other churches, baptism is an act that can be repeated many times in one's life. Instead of being viewed as an act of God toward the one being baptized, it is seen as an act of a human in response to religious conversion or renewal. Some churches baptize all new members because they see baptism as a rite of initiation into church membership so one must be re-baptized each time one becomes a member of a new congregation. Others see it as a sign of Christian commitment that is done as one feels revived or renewed in one's spirit. All of these view baptism as an act that is done by a human in response to something God has done instead of an act of God done on behalf of a human to show God's grace working in their life.
The Early Church wrestled with how much water was required for someone to be baptized. The dry conditions of the Middle East often did not allow enough water for immersion to take place so the Early Church finally decided that 3 drops of water were all that were required for Christian baptism to be valid, a drop for each of the 3 members of the Godhead. That may be why so little water is used in baptizing infants or consenting adults in mainline Christianity. Immersion is accepted in those churches but rarely do people choose it as their preferred method of baptism.
Baptizing infants is linked to the Early Church through scripture passages primarily in the book of Acts that say that when a leader of a household was converted to Christianity, he and his entire household was baptized. Christian scholars believe that children who were part of the household would also have been baptized along with the adults. Infant baptism because the accepted rule of baptism in the Roman Catholic Church and was adopted by mainline churches that resulted from the Reformation that practiced sacraments similar to what they had known in their life within Catholicism. Today, infant baptism is the rule in many churches but older children and adults are given the choice of methods of baptism when they are baptized at an age when they can speak for themselves.
So, what does this mean to Christians who may wonder why we need to be baptized at all? Baptism is an act that one does to show one's desire to follow Christ and imitate his life. Since Jesus was baptized then the followers of Jesus are also to be baptized. Baptism is an act that marks the beginning of the Christian journey through life. We believe and teach that one receives the gift of the Holy Spirit at the time of one's baptism and the Spirit continues to refill and bless that one to empower and equip him/her for the journey. Receiving Holy Communion, studying Holy Scriptures, and praying also invites the activity of the Spirit within the life of believers. Baptism marks the beginning of the walk with Christ. Then, Christians receive the means of grace to sustain them on their journey of life.
Remember your baptism, and be thankful---we often hear this phrase at a renewal of baptismal vows or when we see a baptism done in our churches. What it means to us as individual Christians is to be thankful that God has claimed us through baptism and is reviving us daily as we look to God as the source of our faith and strength.