It's almost never necessary.
But we are so sure we are right and our brothers are wrong.
We should have learned long ago that we don't always see things clearly.
Way back when the Israelites first divided up the promised land, and settled on both sides of the Jordan river, they did the same thing. The people of Reuben, Gad, and half of the people of Manasseh lived separated from the others, so they built an altar there, a copy of the tabernacle where the rest of their people worshiped, so that they would not forget God's faithfulness even though they lived separately.
And what did their brothers in faith say? Did they slap them on the back and say "Good job. So happy for your faithfulness!" No, of course they didn't.
How could you break faith with the God of Israel? How could you turn away from the Lord and build yourselves and altar against Him now?--Joshua 22:16
They didn't get it at all.
So the Reubenites and Gadites set them straight:
The Mighty One! God! The Lord! He knows! ...It is to be a witness between us and you and the generations that follow that we will worship the Lord...--Joshua 22: 22,27
A witness between us and you.
To unite, not separate them.
More often than not, the God we worship is the same God.
Our sects and denominations are not supposed to separate us. They are incidents of upbringing and location. They are different flavors of the same Living Bread.
Some people like statues and stained glass, some a bare cross.
Some prefer loud music, some stately, some none at all.
Some dunk, some sprinkle.
It doesn't have to matter.
Though separated by differences that sometimes seem as wide as the Jordan, we need not destroy one another.
I don't always agree with my husband, but we almost always present a united front to the world.
Why can't Christians do the same?
Stop nit-picking your brother and put your arms around him.
There is one body and one Spirit, even as you are called in one hope of your calling; one Lord, one faith, one baptism, one God and Father of all--Ephesians 4:4-5
Do you see it differently?
Do our denominational differences really matter all that much?