John put a twist on it all by also baptizing Jews, showing that their unbelief and faithless lifestyle had, in God's eyes, put them on the outside. Jesus was baptized by John, showing that He too was part of this great community, this special work that God was doing among His people. John 3.26 tells us that Jesus and his disciples picked up this practice of John the Baptist and also baptized people, welcoming them into the new relationship with God, the community of believers fully devoted to the Lord's service. That's a command. It's like a wedding ring.
Someone makes a vow to be joined body, mind and spirit to another person.
There are two central meanings that the Bible presents to us in Baptism. As the water touches our body, so it symbolizes that our lives have been touched by Jesus' blood. As water cleans and refreshes skin, so baptism symbolizes that our lives are cleaned and refreshed by the Holy Spirit. Many New Testament passages speak of baptism as washing. It means we stand before God without guilt, without the sentence of eternal death hanging over our head.