God disposes his grace to us as befits our nature as well as according to His purpose. We are created from the earth, we are physical beings. Throughout the Scripture, Old and New Testaments, the blessed Trinity uses physical means as signs of inward grace. Think, for example, of the Covenant with Noah, where he uses a rainbow and sacrifice to compact his love for Noah, his family and their offspring. God could have chosen to just use an inner spiritual sense to manifest this if He had wanted to.
This pattern does not cease in the New Covenant with Jesus and us, as His brothers and sisters. In keeping with the steadfast love of the Incarnation, God the Father sends Jesus to use water, mud, wine, bread and fish to manifest the inbreaking of the Kingdom. If he had wanted to, God the Father could have sent Jesus in the form of a pure spirit, known only as an inward manifestation. Instead, such is His respect for His created beings, that He sent His Son in human form, so that the human person in all his/her dimensions could be saved. If God did not assume the physical dimension of existence into His grace, we could not be saved bodily, through the Resurrection. Yet, it was His will to save the physical creation, with the human person as its pinnacle, by taking on and using the physical world to accomplish His good purpose.
If this doesn’t convince you, try listening to Scott Hahn’s tapes on the seven Sacraments, available from St Joseph Communications. He quotes chapter and verse and expands more eloquently than I could on how the sacramental view is the only scriptural view there is. Only Catholicism and Orthodoxy take our physical nature seriously enough to be able to proclaim legitimately, “I believe in the Resurrection of the dead”. And if there is no Resurrection, as St Paul said, we are most to be pitied of all men (and women).
God’s blessings of the Covenant of Jesus be with you.