Belief systems help to shape our worldviews and the ways in which a culture organizes life. You may be surprised to know that even in highly secular societies, religious plays a major part in shaping society.
The archaeological record suggests that as long as the human species has existed, we've had questions about our world, though not always the means to answer them. One suggestion about the origins of religion is that supernatural answers could explain questions about natural phenomena. It is harder to know what our ancient ancestors actually believed, but we can make some inferences based on what they left behind. For example, the burials at Shanidar cave of several members of a population of Homo neandertalensis (our "cousins" in the Homo lineage) display purposeful burial. From the finding of flower pollen around the bodies, we can infer a respect for the bodies of the Shanidar dead, and perhaps a supernatural belief about what happened to those people after death.
Supernatural beliefs work on a scale from localized folk-belief to organized, often wide-spread religion. They also may function overtly or covertly in a culture. Most people, upon hearing a sneeze, will say something along the lines of, "Bless you." This in itself is not a religious or spiritual practice, and many secular people offer such blessings when hearing a sneeze. The origins of this commonplace cultural practice, are religious, though. Another more covert function of religion is society is the way in which we organize time. Many cultures consider Saturday and Sunday to be the "weekend-" a time to abstain from work and enjoy leisure activities. This has long been practice in cultures where the Abrahamic traditions prevail (Judaism, Christianity, and Islam), as Saturday is the Jewish Sabbath and Sunday is the same for Christians. This is a predominantly Western practice, though it has spread to other parts of the world. Even in cultures which are not officially religious, and for people who do not ascribe to organized religion, abstinence from work on the weekend is a regular part of many people's lives.
The degree to which religion influences life may be impacted by other cultural elements such as language and education, geography, ethnicity or race, and societal or governmental structures. As an anthropologist, I favor the idea that science and religion are equally valid and serve the same purpose in life- to answer questions we have about the world. However, as technology has advanced throughout history and continues to advance, the ability to quantify the world around us can make religion seem less important. Supernatural belief has always helped humans to make sense of the unknown, and we can be sure that as we answer more questions about our world, new ones will always arise. Engaging with the supernatural, whether it be through organized faith or hoping it wont rain tomorrow, offers humans a sense of comfort in the face of the unknown.