Thank you all for your thoughts and recommendations’. What I finally wrote back follows. I looked to the United States Conference of Catholic Bishops after having checked my Diocese web site. This seemed to answer the question well enough without getting to technical and keeping it at the higher level of why Protestants generally cannot receive holy communion while still participating in celebration of the Eucharist.
“Below is the text I found. I cannot explain why you were allowed to receive communion on occasion at the Dominican Retreat House or by Father Bob, other than they may have been granted permission by the Archbishop or they did not know you were no longer part of the Catholic Church. I was present at least one time at the hospital when you received communion and I do not recall you stating to the lay minister that you were not Catholic.
“On November 14, 1996, the National Conference of Catholic Bishops approved the following guidelines on the reception of communion. These guidelines replace the guidelines approved by the Administrative Committee of the NCCB in November 1986. The guidelines, which are to be included in missalettes and other participation aids published in the United States, seek to remind all those who may attend Catholic liturgies of the present discipline of the Church with regard to the sharing of eucharistic communion…”
“We welcome our fellow Christians to this celebration of the Eucharist as our brothers and sisters. We pray that our common baptism and the action of the Holy Spirit in this Eucharist will draw us closer to one another and begin to dispel the sad divisions which separate us. We pray that these will lessen and finally disappear, in keeping with Christ’s prayer for us “that they may all be one” (Jn 17:21).
Because Catholics believe that the celebration of the Eucharist is a sign of the reality of the oneness of faith, life, and worship, members of those churches with whom we are not yet fully united are ordinarily not admitted to Holy Communion. Eucharistic sharing in exceptional circumstances by other Christians requires permission according to the directives of the diocesan bishop and the provisions of canon law (canon 844 § 4). Members of the Orthodox Churches, the Assyrian Church of the East, and the Polish National Catholic Church are urged to respect the discipline of their own Churches. According to Roman Catholic discipline, the Code of Canon Law does not object to the reception of communion by Christians of these Churches (canon 844 § 3).”
I hope this helps you understand the requirements of receiving communion in the Catholic Church. I did not mean to offend anyone if I did.”