“Anyone who is not against you is for you" (Luke 9:40).
In a few sentences, Jesus lays down the basis for collaboration that might have prevented a long, violent history of religious wars, sectarian squabbling and inter-communion competition. "Anyone who is not against you is for you." Anyone who is working to achieve the same goals you have is your ally, not your enemy. Find common ground. Work together.
John, one of the Zebedee brothers, nicknamed the “Sons of Thunder" for telling Jesus to call down fire on a village that did not welcome them, proudly tells Jesus that they tried to stop someone not of their group from performing exorcisms in his name. Jesus rebukes him for his narrowness and presumed control of the power Jesus himself saw as freely given by God to anyone with faith.
Theologian Fr. Peter Phan once challenged missionary attempts to establish Catholicism in pluralistic countries by competing for converts, constructing parishes and denigrating other religions. He suggested a more upside-own approach by starting with dialogue, sharing efforts to do works of justice and address basic human needs. All faith organizations should join together with other humanist or non-religious groups to achieve common goals. Then, when relationships have formed, groups can talk about their theologies.
How quickly and credibly religions would help create a better world if they took this approach instead of calling one another inferior or in error about God and the right path to God. Religion has been a factor in some of the most brutal wars in human history. How often God is used to justify violence. How often claims of orthodoxy have impeded interreligious and ecumenical dialogue that might have averted divisions and fostered unity. How often worthy projects have been marred by quarrels over who should get credit for their success.
Jesus would have none of it. He wanted his Apostles to see the Holy Spirit at work in the world and in everyone who was doing good. And most of all, Jesus was defending the freedom of God to work through anyone who sought the common good, healing and service to others.