Living in harmony is the same as seeing each other as being on the same level, and agreeing together on where we are called to go, or what we are to aim at.
As Christians we see each other as equal participants of God’s sovereign grace and we agree to aim at genuine love for all man-kind.
We are not to be so headstrong and absorbed in self-confidence that we cannot hear the wisdom God speaks through others.
Jesus lived and taught this way, also it points to the glory of God's grace.