Father, Son, and Holy Spirit worked inseparably in creation, making the universe out of nothing. The three persons also worked inseparably in bringing about atonement for our sin, offering up Christ to satisfy divine justice in the face of our sin. They work inseparably in all aspects of redemption, in fact, including our sanctification.
In Ephesians 2:18, the Apostle Paul tells us that the three persons also work as one in bringing unity between Christians. The context of this text is God’s purpose to dissolve the wall between Jews and Gentiles and to make them one people of God in Christ (vv. 11–22). Today’s passage emphasizes the theological grounding of our unity in Christ. Whether we are Jew or Gentile, we have access to God the Father in the same way, namely, in one Spirit through Christ. Christian unity is a consequence of our salvation, which comes from the Father through Christ in the ministry of the Holy Spirit. We enjoy this salvation by means of our regeneration in and by the Spirit, who brings us to Christ, through whom we are reconciled to the Father and brought back into a right relationship with God. The means of the triune God’s working is from the Father through the Son and in the Spirit. The means by which salvation is applied to us and made effective operates in reverse. It is in the power of the Spirit who brings us through Christ to the Father.
Because all Christians are brought to eternal life in the same way, there can ultimately be no divisions between Christians. We are being built into one body in Christ (v. 16). This does not mean a monolithic unity. As with the operation of the Trinity, there is diversity even as Christians are more and more knit together as one people. But this diversity will not finally compromise our unity. We will be one in belief, one in worship, and one in love for our Creator.
It must be admitted that we do not now see much Christian unity. The visible church is divided. Invisibly, we are already one. All true believers in Christ are united to Him and, as a consequence, are united to one another as well. But the presence of sin and error keeps us from realizing this invisible unity in all its visible fullness. But our triune God has already torn down the divisions between believers, and even now He is laboring to make us one in His truth. This is a process that will not be finished until Christ returns, but rest assured, it will finally be accomplished.