Yes, Christ is who sustains us, both spiritually and literally via the Holy Sacrament of Communion.
A Symbol cannot be a figure of speech and literal as well. Symbols are signs, and when one hits a pedestrian crossing sign, they are not literally hitting the pedestrians symbolized in the sign. They will not be charged with vehicular manslaughter.
Signs or symbols are substitutions, but a pedestrian crossing sign does not literally provide a substitution for yet another pedestrian crossing sign. They are a substitution for actual crosswalks up ahead that may have actual pedestrians in them.
You're playing fast and loose with figures of speech with nothing to back up this belief of yours. If we can all do this, then we can take Peter's vision and say that he is literally telling us to "kill and eat" gentiles which is what are being symbolized in his vision. We know this because he informs Cornelius of this revelation as soon as he visits him.
He tells Cornelius' household that he is no longer to refer to gentiles as unclean. They are now acceptable as food to be eaten. See how that works? We can do this all day, and come up with all sorts of interesting conclusions by taking figures of speech and using them literally as well. What's to stop us once we get started?