Baptism (from the Greek word baptizó) is an important rite that exists across almost all Christian traditions. In many, but not all Christian churches, baptism is the act that admits the participant to membership in the church.
"Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God".Luke 18:15 and Mark 10:13 are taken by Catholics and Orthodox as scriptural support for the practice of infant baptism, together with Luke 2:22-24 (presentation of Jesus in the temple), and those texts in the book of Acts which mention whole households being baptized by the apostles of the Lord as most probably having babies in them. They reason that if the blessing of Christ benefited children and babies, being received by them in their souls, the blessing of the grace of the Sacrament of Baptism can likewise be bestowed on infants, and be received by them in their souls. Because of this, infants are baptized a few weeks after being born. In the Catholic ritual, water is poured (infused) over the head of the child while the priest repeats the baptismal formula of Matthew 28:19--
"I baptize you (name) in the Name of the Father, and of the Son, and of the Holy Spirit. Amen."The Orthodox generally give to infants immediately after baptism their first communion, and confirmation. Those baptized as infants in the Catholic Church normally receive first communion when they have reached the age of reason, and about the age of 12, after being fully instructed and prepared, they may choose as believing Christians making an informed decision for Christ to be confirmed, as "soldiers for Christ". Adult converts to Catholicism are infused three times with water (pouring on the head, leaning over a basin or baptismal font), fully immersed in water (in a tank or pool, sometimes recessed in the floor of the church), or submerged (by standing in water with water poured over the head) for baptism during the Easter vigil. Converts to the Anglican Communion are sometimes baptized by aspersion, a sprinkling of water onto the baptismal candidate or collective group of candidates from an aspergill, a sprinkling implement like a short baton containing a sponge in the perforated tip dipped in blessed water and specially designed for the purpose, or dipping a sprig of leaves, evergreen or palm, in water as an aspergill of nature, and sprinkling with it, or simply the use of one or more fingers dipped in the container or receptacle of water to sprinkle it onto the candidate.
The significance and mode of baptism remain controversial subjects among evangelical Protestant Christians. Some churches believe that baptism needs to take place as an infant (called pedobaptism or in an alternate spelling paedobaptism), while others believe only when a person makes an informed decision for Christ should he be baptized. The latter position is called believers' baptism, and those who follow it cite the following Bible passage in support:
And as they went on [their] way, they came unto a certain water: and the eunuch said, See, [here is] water; what doth hinder me to be baptized? And Philip said, If thou believest with all thine heart, thou mayest. And he answered and said, I believe that Jesus Christ is the Son of God. Acts 8:36-37 (KJV)
In some churches, the water in John 3:5 is assumed to be the waters of birth and being born again refers to spiritual renewal. Thus baptism becomes an ordinance performed after conversion.
Baptists recognize baptism only by immersion and after conversion. The theologian L. L. Clover explains this position in his book The Church: Her Origin, Purpose, Doctrine, and History Baptists consider baptism one of two church ordinances, along with communion, usually known as the Lord's Supper. Baptists consider baptism as the individual believer's commitment to the acceptance of personal faith in Christ. They treat communion as a memorial service commemorating the death, burial, and resurrection of Jesus Christ.
Lutheran and Anglican view
In the Lutheran and Anglican churches, infant baptism by pouring is the norm. Among Christians of the Reformed tradition, including Presbyterians and others who hold to the Westminster Confession of Faith, baptism is administered to both believing adults and the children of a believer, for a public confession and as a sign and seal of God's Covenant of Grace. It is properly administered by dipping, sprinkling or pouring, but is not essential for salvation. Prominent past theologians have taught this doctrine such as John Calvin, as well as contemporary teachers such as R.C. Sproul 
Among those typically identified with the Anabaptist tradition, the Restoration Movement (seen by its adherents as a "restoration" to first century Christianity), and the Pentecostal churches, it is widely held that baptism is necessary in establishing a relationship with God. They practice baptism by full immersion in water, usually accompanied by an audible confession of faith. Such Christians believe it evident that in first century Christianity, as recorded in the book of Acts, baptism was ubiquitous. It is said that, "Of the eleven major conversion accounts in Acts, baptism is explicitly included in ten and never excluded (either explicitly or implicitly)."
Biblical accounts of baptism, with some degree of detail, often include phrases describing the person(s) as going into or coming out of water. This, along with the biblical comparison of baptism to burial, is part of their contention that the early Church practiced full immersion. The word itself is generally recognized by linguists as meaning to immerse or sink. However, many dispute this translation, and say it simply means to wash. For this reason, some Christians baptize by pouring or sprinkling, while others use immersion. By those who support the "washing" definition, it is believed that the wording in Matthew's Gospel that Jesus "went straighway out of the water," (per the King James Version) means only that he ascended the banks of the Jordan River following his baptism.
- Sacraments in the Roman Catholic Church
- Salvation Army does not baptize its members, though they are allowed to be baptized in other churches.
- See commentaries on Luke 18:15 and Mark 10:13.
- The Westminster Confession of Faith for study classes by G.I.Williamson, 1964, pp207ff
- Institutes of the Christian Religion, John Calvin, 1536, trans. 1989, pp.512ff
- Now, That's a Good Question!, R.C.Sproul, 1996, p124-5, 339-342,