Baptism with water is the sign and seal of baptism with the Spirit, as much as it is of the forgiveness of sins. Water-baptism is the initiatory Christian rite, because Spirit-baptism is the initiatory Christian experience.
John StottFor the essence of sin is man substituting himself for God [Gen. 3:1-7], while the essence of salvation is God substituting himself for man [2 Cor. 5:21]. Man asserts himself against God and puts himself where only God deserves to be; God sacrifices himself for man and puts himself where only man deserves to be.
John Stott