In the time of Hazrat Mahdi (as) mosques will be grand and flourishing but there will be no mention to the morality of the Qur'an and the importance of the Unity of Islam

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The Prophet of God said: “In the time of Hazrat Mahdi (as) the mosques will be glorious and flourishing, but they will be devoid of guidance and enlightenment.” That is to say, they don’t mention the system of Mahdi, the unity of Islam, the miracles of the Qur'an. They will be devoid of these attributes.”