Psychology has resulted in many views regarding religion and belief in God. Freud thought God was an extension of the Father figure and a belief individuals should seek to overcome. Jung did not profess to know the answers regarding belief in God, but he theorized that religious experiences may relate to the unconscious mind. Since then, psychology has had many individuals present a variety of views regarding the nature of theism and religion. However, there is no consensus on how and if theism relates to psychology.
However, there have been a significant number of inquiries into the nature of religious belief on human psychology. Studies have shown that certain drugs can induce religious-like experiences. In general, the mental and physical health of an individual can contribute to circumstances that will induce these experiences, making claims of "religious experience" possibly explainable in medical terms (at least for a significant number of cases). For instance, less technologically advanced civilizations have been found to associate certain drugs and religion, further making a case for a link between mind altering circumstances and at least some spiritual traditions.
Alternatively, some evidence suggests individuals can be happier as a result of prayer. They do not benefit from receiving prayers (according to the evidence available), but they can benefit from saying them. However, the correlation between these benefits and the action are open to skepticism. Given the prevalence of the placebo effect in psychological practices and the benefits of self-expression, none but the religiously motivated scientists are ready to jump to conclusions. There is not sufficient data to determine causation.
While it's difficult for psychologists to separate theism and religious belief, the debate has moved into other fields such as evolutionary biology and neuroscience, with individuals hypothesizing scientific explanations for religious belief "in the mind." This is interpreted by some as verifying the validity of religious belief through a means to communicate with God. Others believe it shows that God is something imagined in the brain that does not correspond to an actual figure. Perhaps the most common view, though, is that there is no significant relation between human psychology and theism at least in terms of "an on off switch with regards to whether someone believes." The tendency to believe may be linked to psychological traits that vary between people, such as degrees of cynicism, willingness to trust others, and emotional expressiveness.
Overall, there is considerable tension in psychology surrounding a variety of issues. Individuals on both sides are often prone to biases in how they interpret the data. Perhaps the clearest explanation would be to say psychology has yet to provide anything that is both culturally significant and scientifically conclusive in regards to how belief in God relates to psychology.