According to a hadith: جددوا إيمانكم بقول لَا إِلَهَ إِلَّا اللَّهُ. (Musnad Al-Bazzar 9569) "Say, 'La ilaha illallah' and revive your faith." (Musnad al-Bazzar 9569) When we say 'La ilaha illallah' for the first time, we enter God's religion. But this is not enough. We have to revive our faith again and again. In the life of this world, a person is busy with various activities. He faces many incidents day and night. These experiences keep entering the mind and cover up his mind completely. It is necessary to revive one's faith, bring it again into one's attention and renew it in the mind.  A person has to again bring faith alive into his mind.

We are not in an iceland, in vacuum or in isolation. Rather, humans live in society in the midst of different people. Every moment a person is exposed to external influence. In this situation, revival of faith is necessary. A person has to revive the divine truth which he has accepted. This is "revival of faith", or to renew one's faith again and again.