I agree completely with the above.
First, I am a liberal Protestant and the church I grew up in welcomes everyone to Communion. I may believe that all churches should do so, but that misses the point. As a student at parochial school I frequently was required to attend Mass, and I understood that I was not welcome to participate in Catholic Communion unless I shared certain beliefs and preparatory rituals. Even as a little kid, I knew it was more appropriate to stay seated in the pew than to go up and try to make my own private meaning out of the Catholic ritual.
Second, the general lack of education about religion truly is depressing. Regardless of your spiritual belief, education about religious beliefs (Christian and otherwise) is vital to a meaningful understanding of history, literature, language and current events. It is frustrating and sad to hear someone confuse "Catholic" with "Christian" or Sikhism with Islam. It is even more frustrating, given this country's heavily Protestant history, to find so much ignorance of the substantive differences between the Christian churches.