I grew up in a non-denominational church before the term "mega church" was even coined. The sanctuary was built like a Broadway theater and holds thousands of people. There was, and still is, a place to plug in for every age, every hobby, every interest. The core beliefs of the church fall in line with The Apostle's Creed though it wasn't regularly recited. The messages were, and still are, based wholly in Scripture and there isn't a lot of time (if any) spent on denominational grey area. Check out Neighborhood Church for yourself.
Denominational grey area is the stuff that isn't black and white in Scripture. Most of this grey area is created by man after his interpretation of Scripture. This grey area encompasses ideas or beliefs that do not affect salvation, at least not necessarily. I suppose if one put more belief, more weight in the grey areas than in the absolute truth of the Gospel, then perhaps they become salvation issues. But that, my friends, is a discussion to have in person at another time.
To me, denominational grey area is only beneficial if it is used as a "iron sharpens iron" kind of tool. It should be used to get believers into the Word to read, learn and discover what God has to say about things. Unfortunately, more often than not, denominational grey area is used as a weapon against other denominations or as a marketing tool to get more church members.
A few years ago, I was sitting in a meeting among Christians. To my knowledge, there was only one other non-denominational Christian in the room. The rest were all of the same denomination. One person in the room piped up and said, "Well, our denomination is the only denomination that has it completely right. We are the only denomination focused totally on Christ."
I sucked air, bit my tongue and saved my anger for when I got home. Poor Scott got an earful. You see, not only was this statement insulting, it was accusatory and judgmental. And, it was wrong. Wrong because --and please read carefully--denominations were created by man. Man is sinful. Man has not gotten it 100% right ever.
Denominational grey area usually covers things like the logistics of baptism and communion, leadership roles in the church, methods of worship, and even what we and our clergy wear to church. And none of it will actually earn us salvation. None of it is akin to God's grace demonstrated in Jesus' death on the cross. When we get to heaven -- regardless of where or when that is or what it looks like -- these grey areas aren't going to matter.
You see, when we get to heaven, we will just be the Body of Christ. There will not be a special section for the Baptists or a special area for the Methodists. The Presbyterians do not have a reserved room nor the Lutherans have their own corner.
Here's the part that really upsets me about all of this: non-believers get sucked into, rollled over and turned off by all this denominational grey area rigmarole. It confuses them. It causes them to "church shop." (heck, it even causes believers to "church shop") It causes them to never set foot in another church. And it waters down the true message of the Gospel.
I think if we read 1 Corinthians chapters 1 and 3, we'll find that our denominational grey areas are pretty similar to the divisions and differing opinions/teachings Paul wrote against. He exhorted the early church to find unity, to not boast in our knowledge and to recognize that we belong to Christ alone.
So, go out and discuss your denominational grey area. Use it as a tool for growth. Let your views sharpen someone else and let their views sharpen you. Use it as an opportunity to dig into the Word and study. But, please, when we present our faith to the unbelieving world, please let us focus on that which we agree. Let us proclaim the message of the Gospel that Christ, the only Son of God, came to earth as fully God and fully man, lived a sinless, perfect life so he could be the Perfect Lamb. He was tortured and crucified on a cross. He died. He rose again. He is coming back. And He did all of that for you and for me. So that we wouldn't have to pay for our own sins with our own death. He gave His life so that we can live forever with Him.
NONE of the great theologians whose works inspired the denominations did that. NONE of them could. Only Christ can. Only Christ did. THAT is what we should focus on, THAT is what we should highlight, THAT is the message we should be careful to not water down in grey area.