“Since Jesus commanded His church to baptize (Matt. 28:19), we would expect that there would be a measure of blessing connected with baptism, because all obedience to God by Christians brings God’s favor with it. This obedience is specifically a public act of confessing Jesus as Savior, an act which in itself brings joy and blessing to a believer. Moreover, it is a sign of the believer’s death and resurrection with Christ (see Rom. 6:2-5; Col. 2:12), and it seems fitting that the Holy Spirit would work through such a sign to increase our faith, to increase our experiential realization of death to the power and love of sin in our lives, and to increase our experience of the power of the new resurrection life in Christ that we have as believers. Since baptism is a physical symbol of the death and resurrection of Christ and our participation in them, it should also give additional assurance of union with Christ to all believers who are present. Finally, since water baptism is an outward symbol of an inward spiritual baptism by the Holy Spirit, we may expect that the Holy Spirit will ordinarily work alongside the baptism, giving to believers an increasing realization of the benefits of the spiritual baptism to which it points.”
Wayne Grudem, Systematic Theology, pp. 953-54.