Pantheism is a broad and multifaceted philosophical and religious worldview that asserts the identity of God and nature. It lacks a single, universally accepted definition. Throughout history, pantheistic elements have appeared in various Eastern and Western philosophical and religious traditions, and the system was particularly developed and formalized by philosophers such as Spinoza. In pantheism, God is not considered separate from the universe; rather, God is viewed as identical with nature and existence itself. Accordingly, concepts such as unity, immanence, monism, and determinism are central to pantheistic thought.

Although pantheism is sometimes perceived as akin to theism, it fundamentally differs by rejecting the notion of God as a being endowed with will, knowledge, and power. In the context of the problem of evil, pantheism offers explanations that diverge significantly from theistic interpretations.

The problem of evil centers on the question of how the existence of evil can be reconciled with the existence of God. Within theism, this problem poses a challenge to God’s goodness, omnipotence, and justice. In pantheism, however, the issue is addressed differently, since God is not a personal or volitional being. One of the most fundamental criticisms of pantheism relates to its monistic structure: the identification of God with nature implies that evils are inherent within God or God's nature, potentially rendering God "evil." Another significant criticism is pantheism’s commitment to determinism, which denies the existence of free will and thereby undermines the basis for human moral responsibility.

Pantheists such as Spinoza regard good and evil as relative constructs, arising from human cognition and ignorance. From this perspective, evil is merely a label assigned by humans to certain events based on their perceived self-interest, and it lacks objective reality. The universe operates according to laws of necessity; everything occurs as it must. Consequently, free will is considered an illusion, and neither humans nor God can act otherwise. This deterministic view raises serious questions about the possibility of moral accountability.

The pantheistic notion that evil is merely an illusion has been subject to several philosophical critiques. First, it is argued that the theory is internally inconsistent. If evil is unreal, then the illusion that conceals the pure and untainted goodness of everything must itself be regarded as a form of evil—thus, evil would exist. This means the claim that evil is unreal implies its own falsity. Secondly, the pantheistic view is said to contradict common human experience. The claim that evil is an illusion appears counterintuitive when confronted with real-life tragedies. For instance, it is clearly unreasonable to suggest to a grieving mother who lost her child in an earthquake that her suffering is merely illusory. A third critique concerns the undermining of moral foundations. Denying the existence of evil is sometimes described as the worst possible moral claim, as the pantheistic view, by failing to distinguish between good and evil, effectively erases the basis of moral values. Lastly, critics argue that pantheism renders worship and religious devotion meaningless. While pantheism allows for reverence toward nature or the divine unity, it excludes any personal relationship with God, such as prayer, worship, or divine-human interaction.