For through him we both have access in one Spirit to the Father.
And in a short, out the way verse focusing on our great salvation in Jesus, trinitarian theology pops into view. Jesus, through His death gives us access to the Father as we are indwelt, all of us together, by the Holy Spirit. Our salvation is an active engagement with all three members of the Godhead.
Jesus, God's Son, died for us. In His atonement we are redeemed and put into His family with a new relationship with the Father. Jesus makes us holy so that God's Holy Spirit may now live in us.
The Spirit makes us one. All believers are brought together as a new creation because of the Spirit indwelling each one of us. And in this new Body of Christ, the church, we proclaim Christ's saving gospel and glorify the Father in worship.
The Father is now our Father. We are in Christ's family, co-heirs with Him through the redemption and loved by God the Father. He blesses, leads, loves, and disciplines us as His own children, born again now by Christ's merits and made alive in the Holy Spirit.