The fact that he appears at a time when people are completely distanced from the moral values of the Qur'an will prevent Hazrat Mahdi (as) being recognized

It is reported in hadiths that the End Times will consist of two parts. The first phase will be one in which the world suffers material and spiritual troubles, when people suffer great moral degeneration. The second phase, on the other hand, will be a time of well-being when Islamic moral values prevail over the world, a time referred to as the Golden Age by Islamic scholars.

This first period, when most of the people are totally distanced from religious moral values and chase after their earthly desires, and when excess, perversion and immorality are unbounded, is one of the most important signs of the End Times, in which Hazrat Mahdi (as) will make his appearance. Close examination of these signs, revealed by the Prophet (saas) around 14 centuries ago and referred to as Signs of the Day of Judgment, shows that we are looking at a most extraordinary situation: A great many of the signs of the Day of Judgment have taken place in our own time. This shows that the time when the Prophet Jesus (as) will return to Earth, when Hazrat Mahdi (as) will appear, and when the moral values of the Qur’an will rule the whole world is now approaching. (Allah knows the truth.) On the other hand, however, phenomena such as the present intensity of moral degeneration, the way that what is forbidden is regarded as lawful, the difficulties people have in making ends meet, rising poverty and the way that denial of Allah is now openly expressed, is causing people to forget about Allah and the Hereafter and turn instead to the life of this world. Hadiths reported from the Prophet (saas) describe the turmoil into which the world will fall during the End Times:

Signs following one another like bits of a necklace, falling one after the other when its string is cut. (Tirmidhi)

The Day of Judgment will not happen…until prostitution is blatant. (Ahmad Diya ad-Din al-Kamushkhanawi, Ramuz al-Ahadith, 91/7)

Respect for the old and compassion for the very young will disappear. Children of adultery will multiply. So much so that people will commit adultery with women in the street. (Al-Barzanji, Al-Isha'ah li-ashrat al-sa'ah, p. 140)

Hazrat Mahdi (as) will not appear until innocent people are massacred and the slaughter in the Earth and sky becomes intolerable... (Ibn Hajar al-Haythami, Al-Qawl al-Mukhtasar fi `Alamat al-Mahdi al-Muntadhar, p. 37)

In the End Times scourges from their leaders will afflict my community, so much so that there will be little room for Muslims. (Al-Muttaqi al-Hindi, Al-Burhan fi Alamat al-Mahdi Akhir az-Zaman, p. 12)

Hazrat Mahdi (as) will appear after a corruption in which all forbidden things are regarded as lawful. (Ibn Hajar al-Haythami, Al-Qawl al-Mukhtasar fi `Alamat al-Mahdi al-Muntadhar, p. 23)

In another hadith, our Prophet (saas) describes the confused state of affairs confronting believers in the End Times:

Due to the evils among them he is unable to change or rectify, the heart of a believer possessed of taqwa [piety and fear of Allah] will dissolve like salt in water... (Mufid al-'ulum wa-mubid al-humum, p. 218; Al-Sharani, Mukhtasar Tazkirah al-Qurtubi, p. 456)

The activities of Hazrat Mahdi (as) may not at first be grasped by the majority of people at a time when there is such great corruption going on. People far removed from the moral values of the Qur’an may not fully understand the great intellectual struggle waged by Hazrat Mahdi (as) in order to disseminate his work, his message and religious moral values. They may fail to comprehend that the disorder, poverty, war and moral degeneration being experienced in the world can only come to an end by people living according to the moral values of the Qur’an. This may prevent them understanding the importance and purpose of the work of Hazrat Mahdi (as) and his community. Indeed, on the contrary, the sincere efforts on the part of Hazrat Mahdi (as) and his community to preach the moral values of the Qur’an may make these people uneasy and lead them to back the unjust accusations and slanders made against Hazrat Mahdi (as). They will insist that he and those around him cease their efforts to spread the moral values of the Qur’an. These perverted wishes of those who have no faith are reported as follows in the Qur’an:
 

... They would dearly love you to become unbelievers. (Surat al-Mumtahana, 2)
 

According to the indications in the hadiths of our Prophet (saas), this state of mind that will develop in society in general during the End Times will prevent Hazrat Mahdi (as) being recognized and known by his true titles by the public. It will hinder people seeing the moral virtues of this holy personage and his genuine and beneficial endeavors on the path of Allah.