The ways in which the message is given are different because the mentality of mankind differs at each period. Every prophet had to speak in the manner of the time in which he lived, and according to the evolution of that time. Also, the custom of each country differs from that of other countries; the manners and life differ. If the messenger is born in one country and has to give his message in another country, surely he has to consider the way in which the people there look at life, and to give his message accordingly. But the message is always from God. This is the reason why the external study of Buddhism will make one feel that Hinduism is different from Buddhism, and the external study of Christianity and Islam will make one feel that Christianity is different from Islam; but if one saw that underlying thread that connects all religions, one would see that all religion is one, as truth is one, as life is one, as God is one.