One God and Father of all, who is above all, and through all, and in you all.
In Ephesians 4, the apostle Paul was emphasizing the things that unify Christians. As there is one faith, one baptism and one Lord Jesus Christ (verse 5), there is one God the Father. He is the universal unifying factor. Though He is the supreme authority of the universe, He is willing to dwell with us and to be our Father (2 Corinthians 6:16, 18).
The Father and the Son are completely unified and equal in their form of existence (Philippians 2:6), but Christ stated that the Father has the preeminence (John 14:28). After all enemies, including death, are put away, Christ will continue to be “subject to Him who put all things under Him, that God may be all in all” (1 Corinthians 15:28).