In Reformed theology, baptism is a sacrament signifying the baptized person's union with Christ, or becoming part of Christ and being treated as if they had done everything Christ had. Sacraments, along with preaching of God's word, are means of grace through which God offers Christ to people. Sacraments are believed to have their effect through the Holy Spirit, but these effects are only believed to accrue to those who have faith in Christ.
Baptism is the sacrament of initiation into the visible church, or body of people who publicly claim faith in Christ. Baptism also signifies regeneration and remission of sin. Reformed Christians believe that the children of church members should be baptized. Because baptism is believed to be beneficial only to those who have faith in Christ, infants are baptized on the basis of the promise of faith which will come to fruition later in life.