Q. 94 What is Baptism?A. Baptism is a sacrament of the New Testament, wherein the washing with water in the name of the Father, and of the Son, and of the Holy Ghost, doth signify and seal our ingrafting into Christ, and partaking of the benefits of the covenant of grace, and our engagement to the Lord's.I will endeavour to explain this and to support it from the Bible so that you can better understand what baptism is. Mark begins his gospel with baptism, calling it the beginning of the gospel. He doesn't explain what baptism itself is because it was already known from the Old Testament.