How should we understand the hadith: "One will be believer in the morning and an infidel in the evening?"

"There will emerge mischief in future. In this mischief, the person will wake up in the morning as believer and may reach the evening as unbeliever; except for the people whose hearts Allah revived with knowledge." (1)

This hadith strengthens the hadiths about mischief. Here the point is that mischief and corruption will be extensive. In a Muslim community, a person who wakes up and leaves his house as Muslim may come back to his house in the evening as unbeliever because of a doubt, a word or any other cause with the effects of the community, his friends, media or another source. Here the biggest factor is that the person does not know his religion well, because the one whose heart Allah revives with the knowledge of Islam and truths of faith will be saved. In this respect, it comes to the mind that in the age of mischief and corruption, the number of the ones who knows Islam will diminish, Islamic knowledge will be insufficient, and it will be difficult to convey Islam to the needy.

To summarize, while innovations (non-Islamic elements put into the religion) and debauchery surround Muslims, it will make them earn great rewards for the upright and devout people to stick to the judgments of Islam and to the Sunnat (the way Prophet Mohammad lived). For at that time it is so big a deed even to protect faith.

Sources:

1. Ramuzul-Ehadis p. 299, 3722 hadith. (From Tabarani Kebir, from Ibn-i Mace, from Deylemi Ebi Umame), en-Nevevi, Ebu Zakariyya Yahya b. Sharaf, Riyazus-Salihin, Trans. Emre, Mehmed, Istanbul 1974, p. 99 87. hadith; Sunenu Ibn-i Mace, II, 1305, 1310 (3954, 3961) hadiths.