"To believe in God, you just need to believe, to have faith." I've heard this sort of statement at least a dozen times in my life. But what really causes belief in God and life after death?
A wide range of research suggests that religious beliefs can be altered (to an extent) by certain psychological needs and states. I discuss 5 of these below.
1) A Need for Control
Research by Aaron Kay (now at Duke University) and colleagues suggests that when someone is feeling personal uncertainty, or a lack of personal control, they are more likely to believe that God is in control. The basic idea is that people have a need for control, and when they receive this via secular routes (like cops or the government) they do not have the same need to believe that God possesses control. Evolutionary psychologists have made similar arguments, citing data showing that when economic and health security are high, people tend to be less religious.
2) A Need to Cope with Death
Reminders of death increase people's belief in spirits and the power of prayer. Moreover, having people read that there is life after death (even atheists) reduces people's psychological distress in response to thinking about death.
Kurt Gray (University of Maryland) has conducted several studies showing that people believe in God more strongly after being exposed to unexplained suffering. For instance, if people read of suffering that can be explained (i.e., a man loses his job) this would not increase belief in God. However, if people read that am unexpected flood had caused a family to die, this would increase belief.
Ironically, suffering increases theism.
4) A Need for Justice
When people think that a God that can punish is watching them, they behave more morally. Moreover, they also feel less of a need to punish others. It follows from this research (though the study has not been done) that people should have less belief in God (at least his punishing characteristics) when they are feeling like secular sources of authority are providing ample justice. Somewhat supporting this, religious people have less distrust of atheists after watching a video of police effectiveness.
The need to punish others (who have not been punished) is associated with belief in God.
5) Experiential Thinking
There are (at least) two primary modes of thinking and decision making. One is called experiential thinking, in which a person relies primarily on their "gut" or their feelings when making a decision. The other is logical thinking, in which a person makes a decision in a more cold, calculated manner.
Research suggests that belief in God is higher among people who more often think experientially. Moreover, forcing people to think experientially in an experiment heightens their belief in God, compared to people who are forced to think logically.
In other words, people's natural thinking style could, or could not, lend itself to belief in the supernatural.
I do not mean to suggest that these are the only five factors that influence belief in God. There are many other factors.
I also would like to add that these studies are all conducted measuring a continuum of belief, typically on a scale of 1-5 or 1-7, and the results of each study are dealing with average scores across all participants. Therefore, I am not suggesting that a person with strong belief will suddenly not believe at all (go from a 7 to a 2, for instance) if they are feeling in control, or are not exposed to suffering. I also am not suggesting that a person with no belief will suddenly believe entirely (go from a 2 to a 7) under certain situations.
What this work does suggest is that moderate shifts in belief can occur when people are feeling things, such as a fear of death, a lack of control or a need for justice, and when they are exposed to suffering or are thinking experientially.