The Lord does not approve of divisions in His body; yet we opt to divide over often insignificant opinions, occasionally over something as simple as personality conflicts.
It doesn't take a rocket scientist to realize that unless the divided churches rooted in the Restoration Movement find ways to unite, our prospects of forming any viable unity with churches outside the RM is probably not going to happen.
My overly simplified solution for ending divisions: Perhaps rather than having our occasional (and usually unfruitful) unity conference featuring our most articulate and well known speakers, why not just announce a great big ol' picnic BBQ and allow the conference to take place from table-to-table among the rank-and-file members. If we're truly seeking Christian union then we need to engage the total membership, not just a select few that often present their own thoughts rather than what the congregation desires.
Below are several concessions we might have to live with if any form of unity is realized. There are many more; perhaps you can add others, or give good reasons why we shouldn't concede these:
1. While we may have an aversion to instrumental music we don't have to use it, but we must be willing to allow those who are not adverse to using instruments to do so without condemning them.
2. Churches utilizing one cup, two cups, or hundreds of cups in celebrating the Lord's Supper should not cause divisions, we can choose what we believe to be correct, and let other churches make their choice as well .... it doesn't really matter!
3. Whether to use church contributions for orphanages, colleges, preacher schools, or other places we feel need our help will have to be determined by each church, and respected by other churches that don't agree.
4. Sunday schools are great, and we can continue to use this tool, but for church groups that don't believe it's right, then they should continue Sunday mornings sans the Sunday School System, without either group condemning the other. It should be the choice of each church, and all Christians should understand this is simply a matter of choice and not a life-and-death situation.
We don't have to concede anything that goes against our conscience that we feel is absolute truth, in fact it would be wrong. We just need to realize that as believers we are God's children, and while we may not agree exactly on the scriptures, we can still be ONE in Him.