Jamieson, Fausset and Brown on Ephesians 2:18

18. Translate, "For it is through Him (Joh 14:6; He 10:19) that we have our access (Ep 3:12; Ro 5:2), both of us, in (that is, united in, that is, "by," 1Co 12:13, Greek) one Spirit to the Father," namely, as our common Father, reconciled to both alike; whence flows the removal of all separation between Jew and Gentile. The oneness of "the Spirit," through which we both have our access, is necessarily followed by oneness of the body, the Church (Ep 2:16). The distinctness of persons in the Divine Trinity appears in this verse. It is also fatal to the theory of sacerdotal priests in the Gospel through whom alone the people can approach God. All alike, people and ministers, can draw nigh to God through Christ, their ever living Priest.