There was a brief story I read, where a the writer describes a conservation with a woman. The woman and her family had decided to leave the church they were attending, because they did not feel they agreed with the vision the church had.
The writer recognized that shared vision was important. But he used to story to illustrate something he thought was more important: love and unity.
First, we do need to recognize that in God's kingdom, love is #1. To love God is the first command. First in importance. First in priority. First in practice. Loving people is the second command. Moreover, Jesus gives the two an equivalency. Jesus said, if we serve someone, motivated by love, then we serve him, motivated by love.
Then, love is a primary way that members of his family demonstrate that they follow him. And unity is a primary way that members of his family demonstrate love.
I don't think people realize how serious Jesus took unity. Scripture records one of Jesus' prayers. In it, he prays that, not only will his family be united, but that they will be united with the same intensity, the love, the same completeness as the Father, the Son and the Spirit. And if they are united, it demonstrates the truth, that God sent Jesus into the world.
What if there is no unity? Does it demonstrate that God did not send Jesus? I know of one person, who says God gives the unsaved permission, based on this portion of Scripture, to say that the Father did not send the Son.
Unity takes on a much, much bigger meaning, when seen in this context.