Jesus never prayed for the unity of religions.
Unity to which Jesus calls his followers has a clear focus and purpose. It is the unity in and around Jesus, modeled by and rooted in the loving and mutually embracive relationship between Him and the Father.
Jesus prayed, “That all of them may be one, Father, just as you are in me and I am in you. May they also be in us so that the world may believe that you have sent me.., and have loved them even as you have loved me”. John 17:21-23. NIV
Unity for which Jesus prayed does two things. First, it draws his followers closer to Him. Then, it draws His followers ever closer to each other into a loving community of faith that flourishes above and despite denominational boundaries and overrides religious policies and agendas.
This kind of unity is all about Jesus and none about a common, compromising ground. It approaches all other kinds of ideological unifications in the same way Shadrach, Meshach and Abednego approached Nebuchadnezzar’s attempt to unify all faiths and nations under his rule around the golden image, even in the face of daring consequences.They stated without any hesitation: “We want you to know, O King, that we will not serve your gods or worship the image of gold you have set up.” Daniel 3.16-18.
Followers of Jesus will never advance the cause of religious unity for its own sake, however sweet and desirable such unity might be. Any pursuit of spiritual unity where Jesus is not its center and its purpose, is idolatry and pure deception; a precursor to tyranny, abuse, manipulation, spiritual confusion, and Babylon. Bypassing or undermining the centrality of Jesus for the political, social or religious correctness sake, so that no one is offended, is like ripping the heart out of a body of the living and healthy person, foolishly expecting him or her to become even more alive as a result of it.
The only kind of unity that will last is the one where Jesus Christ reigns as the King of Kings, and the Lord of Lords. In it there is no room for any other god, or shared object of worship. There the words of St. Paul are ringing true for any follower of Jesus: “I consider everything else rubbish, that I may gain Christ”. Philippians 3:8. Free Translation