There are two aspects of God’s realization—Love and Fear. On the one hand, God is very compassionate, and on the other hand, He is very just. When man thinks of the unbounded mercy of God, he develops the feeling which has been called in the Quran, “Loving God Most.” (2:165) Similarly when man thinks of God as being just, he has that feeling which has been alluded to when the Quran speaks of: “those who stand in awe of none but God.” (9:18)
The personality of a believer is made up of these two feelings. On the one hand, he loves God the most. And on the other hand he fears God the most. The love of God is such as is filled with agony. Similarly, the fear of God is such as is filled with the love of God. This is a relationship which man hopes to have with the Being he fears lest He deprives him of His blessings. This is the combination of love and fear which can be felt but cannot be expressed in words.
This is the sign of a high level of realization, in which there is peace as well as agony. A high level of realization implies hope as well as fear. A high level of realization brings conviction as well as uncertainty. A high level of realization embraces closeness as well as distance. A high level of realization is a place where sometimes the believer is sure that he has reached his destination, while sometimes he is in doubt as to whether or not he is on his way to the right destination. At times he has this feeling that he has reached a full stop, while at other times, he is in doubt as to whether he is still at the stage of the comma. This feeling of love and fear is true realization, another name for which is maarifah.
Source: Spirit of Islam, December 2013