They are one in the sense that they are united in Christ, even though they do not know each other, even though they come from different countries, even though they are separated and remote physically from each other. Wherever you go, you ought to be able to tell Christians by their distinctive character.
I cannot be united with a Mary worshipper. I cannot be united with a Catholic who teaches that salvation is by works, not entirely by grace. I cannot be united with some kind of liberal modernist Christian, so-called, who does not believe that Christ is the infallible Son of God, who does not believe that he died on Calvary to make an atonement for those who come to him, who does not believe in the new birth. He is following another religion. I cannot be united with him in the Truth.
There is a very foolish interpretation of this verse, and it is deeply mistaken and extremely foolish. It is the Roman Catholic interpretation which has become the interpretation of the so-called ecumenical movement which you will hear very frequently. The Saviour, they say, prayed that all Christian people, all over the world may be one in the sense that they may all join one big movement, the Ecumenical Movement, and ultimately the apostate Catholic church. So there is one organisation, and Christ prayed for organic, organised unity among all his people. Well that, of course, is an interpretation which betrays a complete lack of understanding of Scripture. This prayer, and its great principle, was answered at once. It does not wait for centuries and centuries for some organisation to come along and organise all Christian people into one organic united, some international church or national denomination. The prayer is that the people of God will be one even as Father, Son, and Holy Spirit are one, in other words, that they may share the divine likeness, that there will be a work in the hearts of true Christians which will mean they all have the same characteristics. No, we are joined together because we love him. So today there will be people worshipping in a remote mountain village in Nepal and they are one with us, because they have the same desire, the same love for Christ, the same marks of the Spirit, the same destiny in heaven, the same general characteristics.