At several recent family funerals a number of my family members who are not Catholic insisted on receiving Communion. How can I better explain our practice of limiting Communion and are there dangers with them receiving?

The Catholic practice of reserving communion to fellow Catholics is fundamentally rooted in two things. First there is a norm of Scripture: A man ought to examine himself before he eats of the bread and drinks of the cup. For anyone who eats and drinks without recognizing the Body of the Lord eats and drinks judgment on himself (1 Cor 11:28-29).
 
For St. Paul, the issue is not only sin, (which might exclude some Catholics as well), but also, the need to “recognize the Body.” Yet a great majority of Protestants do not believe Holy Communion to be the Body of Christ, but only a symbol. Hence they cannot truly say the “amen” that is required to the acclamation, “The Body of Christ.” Thus, out of respect for both them and the Sacrament, we do not ask them to assent in faith to something which they regretfully do not believe.
 
A second reason for not sharing Communion is rooted in the fuller meaning of the Sacrament. In receiving Holy Communion, we do not merely speak of a personal communion of the believer with Jesus, but also of Communion with one another in the Church. But sadly, there are many things that divide Catholics and non-Catholics. In coming forward, one attests union with Jesus Christ, but also union with his Church, and all she teaches. Since this is also what Communion means, it is inappropriate for those who do not share this communion with us to come forward and signify what is not fully true, nor should we ask them to pronounce the “Amen” that affirms this community.
 
Thus, there is no rudeness intended by this practice of ours. Rather, there is a respectful, but regretful acceptance that others do not share our beliefs in certain significant matters.
 
As to dangers, note that St. Paul warns of incurring condemnation if we receive Communion either in serious sin or without discerning the Body. When we consider the meaning of our “Amen” at Communion, it is also sinful to solemnly affirm what may not in fact be believed.