I believe that Church Unity, as some of the other posters have said, already exists in the Fullness of the Catholic Church. I’m not yet Catholic, that said.
So what does this mean for Non-Catholics? From what I gather, both on this forum and out of it, every Christian is in some sense Catholic…in the literal, “Communion with the Pope in Rome” sense. But this Communion is imperfect. The One True Church is our (I am technically still among the number, I suppose, until Easter) Home, by virtue of our Baptism…and so we as Christians belong to the One, Holy, Catholic and Apostolic Church (which is the Church headed by Rome), but we do not take advantage of our blessing…we do not return Home.
The Catholic Church remains our Home for as long as we are Christian. As with a kidnapped child who never knows where his home is, our Home doesn’t cease to be our Home just because we do not recognize it. That, so far as I gather, can only happen when we finally do recognize it as our Home and reject it–whether because of laziness or just because it isn’t what we want to believe; then we become Runaways instead of Kidnappees. This is when we fall from grace…which makes common sense: If you actually recognize something as God’s will, and reject it, you’re sinning, separating yourself from Him. Any Protestant will agree, in principle; the same principle, from what I can tell, applies to coming Home to the Catholic Church as well.
Someone asked why Visible Unity under One Church matters? Simple…Christians today spend more time disagreeing than they do showing a unified faith to the world. This is inevitable: There can only be one Truth, and no one can blame Christians who refuse to “agree to disagree” on issues so monumental as their faith and morals. How can we, though, present a unified Christian effort to provide a moral compass to the world if we can’t even agree on Abortion, Homosexuality, and–in some cases–even something so obviously sinful as premarital sex?! People who look for Faith want answers, and “Just love God” will not cut it…people want to know “How will I know that I love God?” They recognize that a mere sentimental emotional “certainty” is unreliable. The Biblical answer is that you will know by your fruits…and only in the visible Unity of the Church can Christians, with a United Voice, tell the world what those Fruits are.
These thoughts are part of what started the journey which has ultimately compelled me to come Home to the Church. I at first wanted to be part of that Visible Unity…then I later recognized the Truth in that Unity, and realize I couldn’t in good conscience not come home, without being the Runaway (as opposed to the Kidnappee).