Communion has both a religious and non-religious meaning. In its religious context, it refers to the Eucharist, one of the most important sacraments of Christian faith. In a wider, non-religious context, it involves a sense of close connection which ties people together. Pat Mora's poem "Gentle Communion" tends to draw on both aspects of this meaning.
I would suggest that there is a kind of paradox at the heart of this poem, as grandmother and granddaughter are portrayed as sharing a very close relationship, even as, at the same time, there remains a sense of separation between the two. Thus, Mora writes:
Since she can't hear me anymore,
Mamande ignores the questions I never knew
to ask, about her younger days, her red
hair, the time she fell and broke her nose
in the snow. I will never know.
I would suggest that Mora's phrasing from the poem's second line reflects this same idea. Ultimately, there is a powerful gap of experience between the two, representing aspects of her grandmother's life that the granddaughter can never understand. And yet, at the same time, even as there is this distance between the two, on a more fundamental level, that sense of distance, as powerful as it is, is also insignificant when weighed against the closeness of their relationship.
Ultimately, religion is one of this poem's critical themes. Given that so much of her life is still a mystery, it is important to keep in mind that the grandmother's religious faith is clearly established as fundamental to her character and personality. Perhaps even more important, however, is the degree to which the interactions between grandmother and granddaughter (with the grandmother peeling the grapes and giving them to her granddaughter) reflect and are patterned after the ritual of the Eucharist:
She removes the thin skin, places
The luminous coolness on my tongue.
In this imagery, the religious and non-religious meaning of the word "communion" become intertwined together, as the ritual and imagery of the Eucharist is invoked in a purely non-religious context. Similarly, and more importantly, much as the ritual of the Eucharist is a means through which human beings can enter into communion with God, so this quasi-ritual between grandmother and granddaughter acts as a means of bridging the gap between them as they enter into communion with one another.