“If a Catholic receives communion from a Protestant minister, it is generally considered ‘illicit’ or unlawful.”
If you are a follower of Jesus, you are welcome to partake of communion in any Christian church that I’m aware of. It’s a wonderful time to ponder the precious death of our Savior as a community of believers.
Or you can call us anathema, shake the dust off your holy feet, and refuse to share a sacred meal with “Protestants.”
It's not a question of insult or rejection. Catholics are convinced that the Sacrament of the Eucharist signifies,and effects, "full union," just as sexual union signifies, and effects, the Sacrament of Matrimony. This is no exaggeration, but a valid analogy, as we see it.
So I may love you with a sincere love, but that doesn't mean I'm authorized to share the act of marriage with you. That's not to anathematize you or to refuse you something you've a right to expect. That's just to say that, although we may love and respect each other abundantly(and I hope we may do so all the more), we ought not to act out a level of union which we do not, in fact, possess.