So step 1 of a workable solution towards unity was determining a consistent definition of sola scriptura across Protestant lines. Certainly not an easy task, and one that, in my humble estimation has a probability of success free-falling towards nil. There are about as many definitions of sola scriptura as there are denominations, and as Daniel pointed out in the comments of the last post, there are some denominations that are even moving away from this standard of Protestantism. Which, of course, raises a very serious problem - even assuming a consistent definition of sola scriptura, there is absolutely no guarantee that it will produce either agreement in interpretation between diverse groups, or the right interpretation.
As an aside, I realize from reading blogs from younger Christians, particularly those from the pomo-emergent church culture, that there is a strong suspicion of calling any intrepretation objectively true or right. It is a view I once shared, thinking agreeing to disagree or leaving enough fudge room for everyone to get along was a good thing. To a certain extent I still think this is true, however, I am increasingly coming to the convictiont that at least on some things, there is an objectively true & right understanding. But I do not think this understanding is mine, but that of the church catholic, so whenever I say "right" or "true", I don't mean what I personally think is this, but what the church has, at least hypothetically, stated as such. This introduces questions of ecclesiology and the precise nature of the church, which will come in a later post.
Interpretational disagreement is abundantly clear in comparing the 2 classical examples of Protestantism - Lutheranism and Calvinism. These 2 systems rely on the same Bible, and yet have radically distinct understandings of grace, faith, justification and the sacraments, to list off a few of the biggies. For other groups, there are variations on these and other issues; some big, some small and some so subtle as to be almost undetectable to the naked eye. But, and this is a huge but, it is precisely these differences that give each group or denomination a distinct identity. It is how they "brand" themselves in relation to other Christian groups. Even for local churches that are non-denominational or only loosely affiliated with a group, there normally exists differences in theology between it and the church down the road. Needless to say, these theological differences stem from conflicting interpretations & emphases, and asking a church or denomination to give up these differences for the sake of unity is to request a doubly difficult task. They must not only melt away their disctinctiveness, but also, at least tacitly, admit that they do not and did not have it right. The only reason a denomination exists is because they think their way of doing church and theology is best, or at least not as bad as the way other groups do them. To the members, these differences are important and any move away from their standard of faith is potentially a move in the wrong direction. And in conversations I have had with other Christians, I know for a fact that some would view worshipping with other groups that believe differently as a violation of conscience a la Romans 14 and therefore sinful.
So the next step is even more complicated than the first. At the very least we would have to get Protestants to move away from their brandedness or somehow de-emphasize that. In a way, it would be re-defining "Christian" as a term not involving denominations or church affiliations. Which is, of course, what the term meant in the first place but has seemingly become intextricably intertwined with such nuances now. Step 2 - redefine "Christian."