The New Testament gives only two simple ceremonies for the Church to conduct. The first is communion. The second is baptism. Baptism is not necessary for salvation but every Christian should be baptised.
When a person who has converted to faith in Christ is baptised, they go down into the water and then come back up again. The ceremony is a vivid illustration of death and resurrection. So when someone is baptised, they are making a public declaration that they are united with Jesus Christ in his death and resurrection.
They are saying goodbye to their old empty way of life without God and committing to their new life as a follower of Jesus Christ. Baptism is a public declaration of loyalty to Christ, a symbolic way of saying “Jesus is my Lord”.
Baptisms take place three times a year during the Sunday service. It is an occasion when those who are being baptised can invite their friends and family to witness their baptism, and when they can declare publicly their faith in Jesus Christ. It is an important and memorable moment in their lives.