31. I have other sheep that are not of this sheep pen. I must bring them also. They too will listen to my voice, and there shall be one flock and one shepherd. (John, 10: 16)
32. By these words Jesus announces clearly that some day men will have only one religious belief. But how can this unity be effected? The thing appears difficult, if one considers the difference which exist between religions, the antagonism which exists between their respective adepts, their obstinacy in believing themselves in exclusive possession of the truth. All desire unity of faith; but all flatter themselves that it will be made to their profit, and no one understands how to make concessions to his beliefs.
However, unity will be in religion, as well as in all social, political, and commercial affairs, by the lowering of the barriers which separate nations, by the assimilation of manners, laws, and language. The nations of the entire world fraternize already, like the provinces of the same empire. They hasten this unity; they desire it. It will be done by the force of things, because it will become a necessity to tighten the bonds of fraternity between nations. It will be done by the development of human reason, which will make them comprehend the puerility of these differences; by the progress of the sciences, which demonstrates each day the material errors upon which they lean, and detaches little by little the decayed stones of their foundations. If science demolishes in religions that which is the work of men, and the fruit of their ignorance of the laws of nature, it cannot destroy, notwithstanding the opinion of some, that which is the work of God and of eternal truth. By clearing away the accretions of error it prepares the way of unity, religions must meet upon a neutral ground, however common to all.
In order to bring this about, all will have to make concessions and sacrifices, more or less great, according to the multiplicity of particular dogmas. But, by virtue of the principle of immutability that they all possess, the initiative concession should come from the official camp. Instead of taking their starting point from on high, it will be taken below by the initiative individual. It has been operating some time by a movement of decentralization, which is tending towards the acquisition of an irresistible force. The principle of immutability, which religions have hitherto considered as an aegis conservatrix, will become a destructive element on account of the unchangeable creeds. Whilst society marches ahead of them, they will be overflowed, and then absorbed in the current of progressive ideas.
The immobility, contrary to being a source of strength, becomes a cause of weakness and ruin for those who do not follow the general movement; it tears down the unity, because those who want to move forward separate from those who are obstinate in staying behind.
Judging from the present state of opinion and knowledge, the religion which must one day attract all men under the same banner shall be that which will the best satisfy the reason and legitimate aspirations of the heart and mind; which shall not at any point conflict with positive science; which, instead of being immovable, will follow humanity in its progressive march without allowing itself to ever be outrun; which shall be the emancipator of intelligence by admitting only a reasonable faith, that of which the moral code shall be the purest, the most rational, the most in harmony with social needs; in short, that which is the best adapted to found upon the Earth the reign of goodness by the practice of charity and universal fraternity.
That which supports antagonisms between religions is the idea that each one has its particular god, and their pretension to having the only true and most powerful one which is in constant hostility with the gods of the other creeds, and occupied in combating their influence. When they shall have become convinced that there is only one God in the universe, and that he is the same that they adore under the names of Jehovah, Allah, or Deus; when they shall be in accord upon his essential attributes – they will comprehend that one being alone can have only one will; they will extend their hands to one another as servants of the same Master, and as children of the same Father; and they will have made a great stride towards unity.