Sufism is a path that seeks to reunite the soul of the believer with God, to see beyond the Unrealities of the world and to perceive the Ultimate Reality. Between the believer and God's face, the universe is something that obscures the image of God—a hijab/veil that was put in place by the fall of Adam. The Sufi spends life seeking to remove that veil and behold God, from whom being separated is akin to being separated from a lover.
As the Persian mystic and poet Rumi put it, "I want a heart which is split, part by part, because of the pain of separation from God, so that I might explain my longing and complaint to it." Often, the relationship between God and the Sufi is expressed in terms of a relationship between a lover and a Beloved. Union with the Divine is the goal of the lover. For example, Rumi writes, "The minute I heard my first love story I started looking for you, not knowing how blind that was. Lovers do not finally meet somewhere. They are in each other all along." Alienation from God is expressed as estrangement from one's Beloved; it is loneliness, a sickness, and a state from which the Sufi wishes to be free.
The paradigm of the Real and Unreal exemplifies much of the dualism of Sufi thought. According to modern scholar William Chittick, pairs of terms are also common in descriptions of the nature of God: beauty and majesty, mercy and wrath, gentleness and severity, wisdom and justice. When it comes to the problem of evil as commonly understood by Sufis, the qualities most pertinent to understanding why evil exists and how to understand it are most immediately related to God's mercy and wrath. In Sufi thought, God's mercy far exceeds His wrath, and flows in one direction, from Him to humans.
Alongside the spiritual suffering Sufis experienced by virtue of alienation from God, very real problems of physical suffering were also addressed by prominent mystics. Al-Ghazali (1058-1111) considered the problem of evil to be an issue that embodied but one stage on the Sufi's path. But belief in God's exceeding mercy should reassure the Sufi, according to Al-Ghazali, that all things happen by His benevolent will. It is unclear how this resolves the issue of evil in the world, but here al-Ghazali seems more concerned with the impact of that evil on the faith of the believer.
God wills existing things and sets things created in time in order, for there occur in this world and in the transcendent world neither too few or too many, small nor great, good nor evil, benefit nor harm, belief nor unbelief, recognition nor denial, gain nor loss, increase nor diminishment, obedience nor disobedience, except as a result of God's decree and predestination and wisdom and will. What He wishes, is; what He does not wish is not. (Cambridge History of Western Philosophy, Richard Popkin, ed., Columbia University Press, 1999, entry on "Al-Ghazali," p. 169)
God's will is ultimately bound up in what Al-Ghazali calls His "secret," which is predestination. The issues of free will and predestination were by no means clear-cut and uncontroversial in medieval Islam, however, and were at odds with the rationalist philosophy articulated by other schools of thought such as the Mutazilites. Sufi interpretations are essentially rooted in the mystical view of the dependency of all being on God's knowledge, and that all existence emanates from His existence, which is ultimately benevolent, merciful, and loving. Therefore, the problem of evil, while not easily or handily solved in the broad and diverse tradition of Sufi interpretations, is somewhat mitigated by the principle that all of earthly reality is merely dependent on God in the first place. This does not absolve people of their responsibility to obey God and refrain from committing evil themselves, a tendency that Sufis attempt to remedy by following the Sufi path to discipline themselves and train themselves to live in a manner that is pleasing to God.