I realize the following could be construed as merely "semantics" but I really think the move to de-pluralize the term "Church" would be a great first step toward realizing the unity we so often forget is there already.
And so, with that out of the way...
Let's stop referring to local gatherings of Christians on Sundays as "small-c churches."
Instead, let's call these meetings+people "gatherings" or "communities" or "congregations" and leave "big-C Church" to refer to all those who've professed and followed the faith in times past, these days, and days to come.
NOTE: Same goes for the buildings we meet in on Sundays. They can be called: homes, community centers, pubs, parks, fields....anything but "Churches."
(I would love some feedback on this one...comments are open.)