Charles Swindoll comments on Jesus' prayer for unity in John 17:21.
" 'That they may be one,' perfected into a unit - not polarized into 70 different slices of Protestant Christianity – but that there may be one great Christ over one great body. That the world may know its truth. Unfortunately there is a greater loyalty to a certain denomination than there is to the body of Christ to one another.
Frankly, I don’t know of a thing that breaks my heart in the church more today than that. I used to be really narrow, really rigid. I used to listen closely to labels, I used to want to find that out before I gave myself to an individual. Before I loved that person. I wanted to screen them. I wanted to find out where they really were, and then I could say, “Well, we’re one.” But my friend, if a person is in Christ, if he is truly born again, than you are one with that person – regardless of the label or no label. Now believe it or not, that’s biblical truth."
– Charles Swindoll, The Church as God Planned It