Christian unity is at once both a fact and a calling, an indicative and an imperative, both already-eternally-true and always-humanly-fragile.
It is the blessed indicative of the good news about Jesus that, because the Father and the Son are one (united but never conflated), and because the Son has called us by name, therefore we are now one (united but never conflated) with God and one with each other. Unity is a gift given that precedes our choices. Praise be to God.
But in this Christian confession, most indicatives also come with an imperative. "It is so ... so live like it!" the New Testament often asserts. That's what the Apostle Paul seems to be insisting in our 1 Corinthians passage for this Sunday, chapter 1 verses 10-18. "I appeal to you, brothers and sisters, by the name of our Lord Jesus Christ, that all of you be in agreement and that there be no divisions among you, but that you be united in the same mind and the same purpose."
Let us rejoice that the Christian movement is never a cult, wherein one is required to surrender the individual mind and forfeit one's individual will for the sake of some falsely-holy homogeneity. No, we are called the Christian unity, not cultic uniformity. Unity is a choice, because it is a first a gift; such unity never dissolves our differences, it merely softens them so that we no longer have to have our way on everything in order to see the way to God. It is a choice to stand together, to work together, for seek together the word and way of Jesus. Indeed, we are more united as one when each of us, in our own ways and in our own times, commits and recommits to loving our God and loving our neighbor.
Each week begins with the gift of unity; each week ends by our asking, How did we do?