In some countries, baptism is a matter of life and death, as it marks that you have converted from the majority religion to follow Christ.
Baptism is an outward and visible sign of:
Forgiveness and cleansing from sin
The gift of the Holy Spirit
Dying and rising with Christ.
Baptism is an inward and spiritual grace - we are baptised in the name of the Father, Son and Holy Spirit speaking of God's initiative in providing a way of salvation and God's call to us to respond to his grace.
We need to receive baptism rightly - it does not create faith, it strengthens faith.
Baptism of infants assumes the parent and godparents are Christians and intend to bring the children up in the Christian faith.
In the Bible, many households were baptised.
In Colossians, a parallel is drawn between circumcision (which happened to mail children as well as adults) and baptism.