GOD sends Prophets for the education of the people and the progress of mankind. Each such Manifestation of God has raised humanity. They serve the whole world by the bounty of God. The sure proof that they are the Manifestations of God is in the education and progress of the people. The Jews were in the lowest condition of ignorance, and captives under Pharaoh when Moses appeared and raised them to a high state of civilization. Thus was the reign of Solomon brought about and science and art were made known to mankind. Even Greek philosophers became students of Solomon's teaching. Thus was Moses proved to be a Prophet.
After the lapse of time the Israelites deteriorated, and became subject to the Romans and the Greeks. Then the brilliant Star of Jesus rose from the horizon upon the Israelites, brightening the world, until all sects and creeds and nations were taught the beauty of unity. There cannot be any better proof than this that Jesus was the Word of God.
So it was with the Arabian nations who, being uncivilized, were oppressed by the Persian and Greek governments. When the Light of Muhammad shone forth all Arabia was brightened. These oppressed and degraded peoples became enlightened and cultured; so much so, indeed, that other nations imbibed Arabian civilization from Arabia. This was the proof of Muhammad's divine mission.
All the teaching of the Prophets is one; one faith; one Divine light shining throughout the world. Now, under the banner of the oneness of humanity all people of all creeds should turn away from prejudice and become friends and believers in all the Prophets. As Christians believe in Moses, so the Jews should believe in Jesus. As the Muhammadans believe in Christ and Moses, so likewise the Jews and the Christians should believe in Muhammad. Then all disputes would disappear, all then would be united. Bahá'u'lláh came for this purpose. He has made the three religions one. He has uplifted the standard of the oneness of faith and the honour of humanity in the centre of the world. Today we must gather round it, and try with heart and soul to bring about the union of mankind.
(Abdu'l-Baha, Abdu'l-Baha in London, p. 42)
