Q. Can Catholics receive communion in a non-Catholic ceremony?
And that, my friend, is the main reason a Catholic Christian shouldn’t receive communion in a non-Catholic church. The Catholic Church teaches in the True Presence of our Lord in the Eucharist, most other churches do not believe in this change. For a Catholic to receive communion in a non-Catholic church would be saying to the other Christians of that church that he believes as they do. The Eucharist is the source and summit of our faith. Everything revolves around this fact, the fact that Jesus Christ is actually present in the consecrated bread and wine. We would be doing a great disservice to those Christians by going along with their ideology. We ought to provoke their thinking instead and to wake them up from their complacency by simply not partaking of communion and keeping to the truth. In fact, we are not in full communion with each other yet and pretending that we are is not helpful for any member of His Church.