The gateway to the Church
Baptism might rightly also be called the sacrament of new birth in Christ (cfr John 3,3-5) which incorporates us into the very life of the Trinity (cfr Matthew 28,19). At baptism, one’s sins are completely forgiven; the water that is used symbolises the cleansing of the soul of Original Sin, inherited by all people at the moment of conception. It imparts sanctifying grace on the one who is baptised, which means that the Holy Spirit dwells in the soul, sanctifying it and preparing it for eternal life with God.
Incorporating us thus “in Christ”, baptism makes us members of the Church. This stands to reason, since the Church is Christ’s mystical body. It is sometimes known as the “gateway sacrament”, since it is only through baptism that we can receive sanctifying grace and receive the other sacraments.
In short, baptism is a sacrament of salvation (cfr 1 Peter 3,21).