What does the The Episcopal Church mean when it says it allows everyone to participate in Holy Communion? What is meant by "everyone"? Is it "all Christians", "all observant Christians", or "all human beings regardless of baptism"?
Canon 1, section 17 of the Canon law of the Episcopal Church states,
No unbaptized person shall be eligible to receive Holy Communion in this Church.
This restricts reception of Holy Communion to Christians only. Actual practices differ some between Episcopal parishes, with respect to further restrictions on who can receive. I know of parishes where the custom is to allow any baptized Christian to receive, and others which restrict reception to those delay Communion until a later time, for example, until after a course of instruction, which means that some baptized Christians might be excluded, for example those younger than a particular age. Every parishes at which I have attended communion make it public either by posting the information in a prominent place, or by means of an announcement just prior to the Communion part of the Service the particular custom of the parish as far as who can receive communion.
The canons, and the US Book of Common Prayer further restrict who can receive communion. According to the US Book Of Common Prayer, (P. 409) Baptized persons who are living a "notoriously evil life", "those who have done wrong to their neighbors and are a scandal to other members of the congregation", when "there is hatred between members of the congregation", and where there has been hatred, and one side is sincerely repentant, but "those on the other side refuse to forgive"are to be informed privately that they may not "come to the Holy Table until he (or she) has given clear proof of repentance and amendment of life",
In those parishes of which I have personal knowledge, the general custom is that a visitor is welcome to present himself or herself for Holy Communion if that person is eligible to present himself or herself for Holy Communion the parish he or she customarily attends.
Persons who are not eligible to receive Holy Communion, are in some parishes, still welcome to present themselves at the communion rail, in order to receive a Pastoral Blessing.
The Episcopal Church is in a period of evolution and discussion on this.
The official rule is "any baptized Christian."
However, a number of individual parishes and dioceses practice "Open Table" - that is, allowing anyone - even the unbaptized - to partake in Communion.
As a general rule, Episcopalians are much less strict about following rules than (for example) Roman Catholics, for whom restrictions on who can receive Communion are a major point of tension and scrupulosity.