We don’t accept this lung analogy as valid in the first place. The Orthodox Church has the appropriate number of organs, and doesn’t need a third lung. Rome isn’t even a viable donor.
Who are the two lungs that you now have apart from Rome; would that be Constantinople & Moscow? But even though Constantinople & Moscow seem to act that way due to there love/hate relationship, still I don’t see how they could be two lungs as both Constantinople & Moscow are from St Andrew and neither are from St Peter. But perhaps I’m putting words in your mouth; so who would you say are the two lungs (since you say Rome would be a “third”, there must be a first and a second).
If you are trying to say that Orthodoxy is complete without Rome, then how can the apostles be complete without Peter? Do you think that Rome would be made complete by it’s union with Orthodoxy? Or is Rome and Orthodoxy both complete as they are and neither needs the other and it’s just the right thing for us both to remain apart?
What does Orthodoxy have that Rome does not? You might say “the truth” (as in Rome is in heresy). Proving yourself right by saying that the other is wrong might work in political debates, but for it to work here in this forum you would have to bring substance into the argument.
Rome has a better argument. Instead of saying ‘we are right because you are wrong’, they do claim to have something that you do not have. Rome has the Keys of the Kingdom.
But it is exceedingly uncharitable to keep doing this ‘us against you, and you against us’ thing. We both need each other to be the best we can be. Look at the Keys in this way: Just as a priest (in the Orthodox tradition) cannot have a Divine Liturgy unless there is some lay people come to church for the service (the priest cannot serve all by himself), take this principle up a level or two, the Pope cannot use the Keys for the benefit of the whole Church unless his brother bishops are with him in the communion of the whole Church. Your not giving up anything by being in communion with the Pope, anymore than you are giving up something by going to church so that your priest can have the Liturgy!
We all have some sort of bias. I, for one, maintain that both Rome and Orthodoxy are valid and grace-filled right now, even though they are not in communion. You can’t force another jurisdiction out of the Church just by braking communion with it! Some do think so, but I do not. But I do think that both East and West will benefit 100 fold just by the union of inter-communion.
