Each one of these divinely appointed reformers endeavored to accomplish their goal in accord with the possibilities and capacity that were available to them in their particular age and thereby drew the people closer to God. If they had not struggled and made the necessary sacrifices, then government based on God's unity would have never taken off. In this sense, all these Prophets are participants and have a share in this final success.
The accomplishment of the Mahdi should be regarded as the success of all God-worshipping peoples in the line of the Prophets and religious leaders. The Imam's victory is not his own personal victory; rather, with the amazing energy of this Imam this will be the victory of truth over falsehood, of piety over disbelief. It will be the fulfillment of the past Prophets' promise to their followers, and the realization of their ideal for human society.
The accomplishment of the promised Mahdi, in truth, is the accomplishment of Adam, Seth, Noah, Abraham, Moses, Jesus, Muhammad, and all other Prophets (peace be upon them). They were the ones who, through their sacrifices and perseverance, prepared this highway and, to some extent, the people's intellect to accept this call.
The program was conceived and the struggle begun by the past Prophets. Each one of them provided an example through their own conduct and pushed the level of the people's comprehension of God's purposes until the line reached the Prophet of Islam. He outlined the complete program and provided the comprehensive blueprint for the transformation of the world. At the time of his death he handed that over to his rightful successors, the Imams. The Prophet and the Imams, then, endeavored on this path to execute the divine plan for humanity and in so doing encountered severe opposition and made great sacrifices.
Many more years should go by, and many more crises and revolutions must be faced by humanity in order for it to mature and become worthy of the government based on tawhid. It will only be then that the last barrier of disbelief and irreligiosity will be surmounted by the astounding energy of the Mahdi (peace be upon him), only then will the dream of humanity materialize.
The Conduct of the Mahdi
