Esdra,
I think the issue comes down to what we mean, when we say “unity.”
As many Christians teach, there is a fundamental unity of Christians, by the simple effect of their baptism uniting each individual to Christ-- as each individual is united to Christ, each becomes united to each other in some respect, by grace through faith in Jesus. This is a mystical unity, and not entirely apparent all the time, but should be showing up in the way Christians love each other as Christ has loved them. Hence, I am called to love my Baptist and Roman Catholic brethren, among others, even when I disagree with them.
There’s also an organizational unity which is always observable from a human perspective. Where there is one bishop, and the faithful are found in unity with the bishop, who in turn has unity with his fellow bishops, there is an organizational unity. This unity should reflect the true unity found by Christians united to each other in Christ.
However, organizational unity often reflects schisms, sins, and errors. Lutherans and Roman Catholics are not organizationally united, because they believe each other to teach error concerning the Apostolic Gospel of Jesus Christ, and the working out of that Gospel in the lives of the faithful. Until that confessional, doctrinal schism is healed, organizational unity is a sham. One might point out, that within many church bodies where organizational unity is achieved, it may mask serious schisms in faith and practice just below the organizational surface. For instance, Roman Catholics are deeply divided over many issues that threaten their doctrinal unity internally, just like many Lutheran and Anglican communities. When organizational and confessional unity are not in harmony, a breech will eventually show up in the organization.
My contention is, that unity finds some kind of common confession eventually. Something has to give, if multiple confessions of the truth in conflict with each other, are merged into one organizational unity and truth is retained. What the ecumenical movement has been a bit light on, is defining what is changing, and what is new… they want everyone to believe that they are still what they were (old confessions) while becoming something new (new declarations/understandings/doctrines/practice, etc.) It’s just not intellectually honest.
If Christians really want to work out their differences, they have to acknowledge that they exist. Competing truth claims need to be put to the test, bad ones left behind and better ones embraced. That’s much harder work, and the reason many people gave up on the ecumenical movement as a whole. At some point, I find it harder, but more honest, to identifiy what makes my confession of Christ distinct, so that I can engage in loving and respectful dialogue with those of other confessions.
Historically, the role of the ecumenical council achieved this unity of faith and practice. Oh, that it may return again…
Peace to you.