An Anglo Catholic priest in England makes observations about ecumenism here, and they got me thinking.

While we must work for the final goal that we may all be one in Christ, it seems obvious that before we can do much fruitful work in ecumenism, that we need further work on ecclesiology. In other words, how can we have a united church if we are not sure what the church actually is?
As a convert from Evangelical Christianity, and then Anglicanism I can affirm that one of the biggest differences in becoming Catholic is to deal with the Catholic understanding of the Church.
There are two concepts of church which both Catholics and Protestants accept, but they accept them in a totally different way. The two concepts are Catholic and Congregational. They might also be called Universal and Local or ‘Us’ and ‘Them. 
Protestants focus on the Congregational, the Local and the ‘Us’ while Catholics put the Catholic, Universal and ‘Them’ first. Protestants look first to their local church, their local congregation and fellowship and think that is most important. They acknowledge that the whole Body of Christ is bigger than their local church (at least most of them do) They accept that there is a Catholic, Universal ‘Them Out There’ aspect to the Church, but they think it is invisible. The Universal Church is composed of ‘all those who have faith in Jesus Christ known to God alone.’
Because the universal church is ‘invisible’ and known to God alone, most Protestants don’t care a button about visible church unity. Their own local congregation is what matters, and they honestly don’t see a problem with the fact that there are tens of thousands of Protestant denominations. For them all the denominations are simply necessary evils. “You have to worship somewhere, so join the local church you like best.” They think it is an incredible claim that anyone would suggest that one church is ‘better’ or ‘more true’ than another, because what really matters is ‘how much you love Jesus’. The Church you go to is really an irrelevance. Consequently, Protestants are also not much concerned about ecumenism.
This is why when I lived in England after one of the tiresome weeks for prayer for Christian unity I was having lunch with the parish priest and he said in an exasperated way, “The problem with the Protestants is they think the ecumenical movement has been a great success because now we talk to one another and are nice to one another. They never wanted visible unity in the first place, and don’t think it matters. They think we’ve completed the journey and I think we’ve only just made a very tentative start.”
Catholics really do believe that the ideal of visible, historical unity is not only desirable, but possible, and not only possible, but necessary, and if it takes a very long time, well, we’ve been here a long time, and we’ll be here for a lot longer, and it is worth working on. We believe visible unity is possible because, while we focus on the Catholic, the Universal and the ‘Them’, we don’t think it is invisible. We think this Universal Church is real and historical and identifiable and that it consists in the Catholic Church, and you can find one in your local town. It is St Agatha’s or St Agnes or St Anne’s in Anytown. You can go there and kneel down and pray and light a candle, or go to confession or Mass and you are not only in touch with the Universal Church. You’re in one. 
Catholics have a ‘both/and’ ecclesiology. The Church is a local congregation, but it is  Catholic first, and that is what gives validity to the local congregation. The Universal Church is Local too, and Fr Hoolihan is there every Sunday preaching long homilies and celebrating the sacraments. The ‘Us’ of the local church and the ‘Them’ of the universal church are combined, and what Fr Hoolihan teaches in St Agatha’s, Anytown is the same that the Holy Father teaches in Rome (or at least it should be)
I have to admit that if I were making up an ecclesiology I would probably have come up with the Protestant version. It is more rational and sensible. It may be more rational, but it is far less like a Church.