After all they are all good people.
Because Catholics believe that the Eucharist is the real presence, body, blood, soul and divinity of Christ, and 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 {and those who do not profess the Christian Faith} 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 The Code of Canon Law (Canon 844 § 4).
All who are not receiving Holy Communion are encouraged to express in their hearts a prayerful desire for unity with the Lord Jesus and with one another.