An understanding of Adiaphora and acceptance of it is key to fellowship. Adiaphora are things which are indifferent or areas where there is truth but not of a significance to divide over.
You see Paul using the concept in several cases where he gives his opinion but says that unity is more important than everyone accepting the truth on the issue.
The existence of Adiaphora indicates that some things are worth fighting over. You see Paul for example confronts certain apostles because they were clearly in the wrong on an issue. And some things are of small importance and unity is more important than this or that tiny detail.
We always need wisdom as we approach scripture. God thinks differently than we do many times. We tend to think as people in either of two ways: in completely black and white terms or completely in shades of gray.
God's thought does not fit neatly into this mold. At some points God's thought as recorded in scripture is completely black and white. In some areas he thinks in shades of gray.
You see God looks at the big picture and that is what wisdom is. It is a call to apply the truth of scripture uniquely to each situation.
There are absolutes but also there are many unique situations with great complexity. There is black and white and there is gray all in life and ethics.