I believe it's wrong for any Christian to be ostracized by a Christian church who denies them communion. Yes, ostracized is the right word. Wouldn't it be more in the Spirit of Christian love & unity to simply tell the congregation that "By receiving communion we believe that you are receiving the body and blood of Christ." Then let those in the pews decide whether they wish to receive.
Afraid that a non-Catholic will will offend Christ by taking "Catholic" communion? Really ??
When I think of Roman Catholicism, I think: power, control, rule driven, mixture of law and grace, strange doctrine, usurping Christ's role. Now to be fair, some of these elements exist in most churches but frankly, the RC church has more of these elements than any other church that I know of.
Regarding closed communion, it has been practiced by Protestants for several hundred years. And it was that practice of “ostraziation” that you used, that resulted in The Christian Church (Disciples of Christ) grew out of two movements seeking Christian unity that sprang up almost simultaneously in western Pennsylvania and Kentucky – movements that were backlashes against the rigid denominationalism of the early 1800s.
Presbyterian ministers Barton W. Stone in Kentucky and Thomas Campbell and Alexander Campbell in Pennsylvania and West Virginia were the leaders of this movement that was part of the Restoration Movement of the Great Awakening between 1790 and 1820. The 3 ministers believed that communion was given to us by Jesus and it was not for a denomination to refuse communion to any professing Christian.
See also: http://disciples.org/our-identity/history-of-the-disciples/
If the Catholic Church is all wrong, as you say, why would anyone want to be in Communion with this false thing? For that’s what it means, Communion with Christ, including His Body in all times and all places.
And on the other hand, if the Catholic Church’s doctrines are true and her Communion IS worthy of adherence and belief, why would a person want to receive Her most precious and sacred Sacrament illicitly, without being received into the Church?
IOW: it’s a matter of honesty.
If you don’t believe, don’t receive.
If you DO believe, you need first to be received into the Catholic Church, and Holy Communion is one of the Sacraments of Initiation.
And you would be as welcome as the flowers in May!