For theologian Wayne Grudem “means of grace are any activities within the fellowship of the church that God uses to give more grace to Christians. He then lists eleven means of grace, which includes water baptism.
According to Grudem, “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.”
For Grudem, this favor and measure of blessing involves the work of the Holy Spirit.
“[I]t 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 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 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.”
Per the above, Grudem believes it is the Holy Spirit working alongside water baptism which makes it a “means of grace” and not an empty ordinance. The Apostle Paul would agree, “For we were all baptized by one Spirit so as to form one body–whether Jews or Gentiles, slave or free–and we were all given the one Spirit to drink” (1 Corinthians 12:13). We simply cannot separate the Holy Spirit from his work in baptism.
Reference: Wayne Grudem, Systematic Theology (Grand Rapids, MI: Zondervan, 1996), 950, 953-54.