The really tough thing to talk about is ecclesiology, I think. For us, it's part and parcel of our Eucharistic practice. I think the fuzzy area is the eschatological aspect of the Sacrament (as we call it). I mean, ONE Day, God willing and me not messing up too much, I will be good. In the meantime, I dare to take to myself the status of goodness because I trust in God's love despite my actual lack of goodness.
One day, all the saved will be in one congregation, "casting down [our] golden crowns around the glassy sea." So there's a part of me that says, since I am, as it were, kiting the check of my future goodness, why not kite the check of our eschatological unity?
I guess from one point of view, the outrage of one Christian saying to another, "I'm sorry, you cannot share in this with us," ought to spur us to greater efforts to work through our differences.
All the saved ARE NOW in one congregation...And it doesn't involve the word Catholic...
Rom 10:9 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.
Rom 10:10 For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.
You apparently don't believe that, or I suspect you'd still be able to call yourself Protestant...