I have to disagree with you here. I understand what you're saying, and there's a lot of good in it... but in the end, what you're essentially saying is that we just have to muddle through, trusting in our own minds and arguments -- sure, pray for wisdom and guidance, but in the end it's all up to us.
The problem is that you've left out the Holy Spirit -- flat shut Him out of the room. But that's wrong: And I will ask the Father, and he will give you another Helper, to be with you forever, even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him, for he dwells with you and will be in you. (John 14:16-17)
Again -- we see very clearly on these threads and elsewhere our tendency to argue about God and what we and others should do and think, but the tone is the same as how we argue about what to do with our senile old relatives. We seem no more willing to let God voice His own opinion in these debates, than we are willing to listen to what poor Aunt Gertrude has to say (after all, she's too nuts to say anything worthwhile).
That's a real and pressing problem -- in my own experience I've seen up close the ghastly damage it causes. Perhaps the worst part is that we tend to dehumanize each other -- you're reduced to a icon representing "issue," rather than a brother or sister in Christ. That's the devil's work.
And, interestingly, I've also seen up close what happens when we allow the Holy Spirit help us work through the very same differences.
How we approach the issues really does matter. If we approach our differences in love and humility, trusting in the Holy Spirit, we often learn that a lot of those huge, intractable problems really aren't all that important after all.
It doesn't mean that differences can't be difficult or important, even to the point of meriting division. Sometimes they do. But mostly they don't, except that our prideful behavior drives us to split over trivia.
I know my own tendency in this direction. I'm prideful, and love the beauty of my own opinions. I struggle with it -- though I think I've gotten a lot better over time.
No. The end is all up to God. The middle is up to us.
I've basically come to reconcile myself with the fact that there are very few simple, easy answers. I really don't think we're meant to have 100% clarity and unity in this life. There are the tentpole truths that the Holy One has set before us so that we can be saved from our sins and walk with Him--we have all sinned and fallen short of the glory of God, but our Father loved the world so much that He gave His one and only Son so that whosoever believes in Him would not perish, but have eternal life, and those who are truly in that Son will be proven by their fruit--but beyond that there are as many different perspectives as there are people.
And I'm not saying that pessimistically! I've come to believe that there is value in the struggle. Jacob was only named a Prince of God after he wrestled with God (Israel means both). The very center of the Torah is to diligently inquire. On many issues, seeking the questions is more important than always having the right answers.
When someone says, "We need to have unity," what all too often happens is that wrestling with God takes a hindseat to not rocking the boat.
So yes, I believe that some of that is on us. Give me a true prophet and I'll heed his words, let the Son of Man speak and I'll bow before Him, but on everything else we have to admit that there are going to be disagreements.
And that's okay. Families can disagree, and still be a family.
Shalom.