How can we have unity among Christians if as Catholics we aren't united?

“In the Church, therefore, there is a variety, a diversity of tasks and functions.

"There is no dull uniformity but the richness of the gifts that the Holy Spirit distributes.

"There is communion and unity: all are in relation to one another and all combine to form a single vital body, profoundly connected to Christ.

"Let us remember this well: being part of the Church means being united to Christ and receiving from him the divine life that makes us to live as Christians."

(Pope Francis, June 19, 2013)