The baptism of Ephesians 4:5 is water baptism because water baptism is for everyone who believes. It is for everyone to obey. It is the baptism that Jesus commanded the disciples to practice. It is the baptism that we may preach and command today. Holy Spirit baptism was limited to a few. It cannot be obeyed. It was not commanded to the disciples, and only Jesus administers it.
God is the Father of All because 1) He created All in His Image, 2) He gave His Son for the All the World, 3) He Treats All Without Partiality. The hearer should understand that no one is excluded from a relationship with God. The only barrier is whether we want one or not. The point of this sermon is to remind Christians that God wants everyone in His body, the church.
Christian unity is based upon Christian teaching. We are united as Christians and without the teaching we are not Christians. This teaching is summarized in the list of seven “ones” in Ephesians 4:4-6. Each person should understand that for us to have unity as Christians we must adhere to the same standards of Christian teaching.