Does anyone on this forum know if the Armenian Apostolic Church is in full Communion with the Vatican? Is a member of their Church allowed to receive Communion at a Mass? Is a Catholic permitted to do the same?
The Armenian Apostolic Church is one of the Oriental Orthodox Churches, which also includes the Coptic Orthodox Church and Ethiopian Orthodox Church. They are not in communion with Rome and are also separate from the Eastern Orthodox Churches. There is the Armenian Catholic Church which is one of the 23 Eastern Catholic Churches and therefore in communion with Rome.
I imagine the rules surrounding receiving Communion would be the same as those for any of the Eastern Churches not in communion with Rome. I forget the canons for that, so someone else would have to help with that.
The Armenian Apostolic Church is not in full Communion with Rome, however a much Armenian Catholic Church is in full Communion with Rome. Both use the same Liturgical books and celebrate the same Liturgy and Traditions. The Armenian Apostolic Church has a fairly good relationship with Rome. Both Churches allow Sacramental sharing among laity for certain circumstances or with Episcopal approval.
I think another important question is whether or not they even have a valid line of Apostolic Succession considering they call themselves an Apostolic Church. If the line of Succession was broken, they have no Apostles and therefore their Holy Orders, Confessions, and Holy Eucharist are all invalid. That means no Holy Spirit at Holy Orders, no real Absolution at Confession, and no Real Presence of Jesus Christ in the Holy Eucharist (as in - the Eucharist in their churches is really not the Holy Eucharist and is really just bread and wine - similar to a Lutheran church or an Episcopalian Church).
Heresy and Schism… really put people in danger of losing their souls
This could get into a very long discussion, but just in terms of one church recognizing another, Catholics recognize Orthodox sacraments, but not necessarily the other way around. (Those more familiar with the Christian West might compare it to the Catholic-Anglican situation.)
The Catholic Church recognizes the Armenian Apostolic Church to be a true Church with valid sacraments.