Turretin writes (Elenctic Theology Bk III, Q22.2):
Our union with Christ and communion in his benefits, which are represented to us best by eating and drinking, as the food eaten by us is most intimately united with our nature and coalesces into one with it. Hence the partaking of the symbols is called the "communion of the body and blood of Christ" (1 Cor 10:16) and Christ is said "to dwell in us, and we in him" (Jn 6:56). And he thus dwells and is united with us that we can call ours whatever is his.
(Interestingly, union with Christ, seems to be the best framework for uniting insights from the New Perspective on Paul with traditional Reformed soteriology.)