“All love craves unity. As the highest peak of love in the human order is the unity of husband and wife in the flesh, so the highest unity in the Divine order is the unity of the soul and Christ in communion.”   — Abp. Fulton J. Sheen

The greatest intimacy this side of Heaven between Christ and His bride the Church is Eucharistic intercourse. While faith and Baptism ratify the covenant by the act of consent, leading to a union of wills, it is holy Communion that consummates the union between Christ and His bride with the two becoming one flesh.

Therefore, Catholics and Orthodox who possess apostolic succession and receive Holy Communion enjoy the intimate marriage with Christ that God has willed for His Church. Protestants, on the other hand, without the intimacy of Eucharistic communion, are in more of a friendship-marriage with her divine bridegroom, that is, what we might call a Josephite marriage: There is consent but no consummation; a union of wills but not of bodies. They enjoy communication the word, but not of the complete self. 

Catholics and Orthodox seek not only seek to know and do His will through His word, but also, and more primarily, seek ontological union with Him through His sacrament.