What is a worldview? A generally synonymous expression is a philosophy of life. A less common way of expressing it: a worldview is a person's religion.
Religion is not limited to such descriptors as Buddhism, Islam or Christianity or atheism (yes, atheism is a worldview and a religion). A religion is a set of beliefs that bind all of life together, that answer the deepest questions a person might ask. Typically, these questions take a form such as, What is real? Where did all this come from? Where will it all end? Is there life after death? What do we know with certainty? Is there such a thing as absolute truth? Is there some purpose that gives meaning and significance to all of life?
Everyone has a worldview. Not everyone knows exactly what their worldview is. Evidence of our worldview shows up in all of our major choices in life. What do I want to be when I "grow up"? Why? Who am I willing to marry? Why? How much money do I want to make? Why? Who qualifies to be worthy of my respect? Why?
It's usually the Why? questions that probe a person's worldview. Actually, the answers we give to these questions comprise our worldview.
Worldviews usually take on their own nomenclature. There are words that we use to capture the essence of a worldview. For example, atheism is a worldview in which the existence of God or a god is denied. Theism is its opposite. If a person believes that the truth of any given proposition fluctuates from one situation to the next or from one culture to the next, he or she operates within the framework of relativism. Pluralism holds that no one worldview (religion) is any better than another. They are all pretty much the same and have equal claim to the truth--even if competing worldviews claim the very opposite of what their opponents claim.
What is the connection between worldview and religion? Why might we consider that these terms are synonymous? The word "religion" at the root level conveys the idea of a binding together, an underlying principle or strongly held belief that connects one person to another, or repels one person from another. We are all creatures of worship. We all bow down to something. The atheist is as much a worshiper as the theist. The only substantive difference between them lies in who or what they worship. The theist worships what he or she regards as God or god. The atheist worships himself since he accepts the existence of himself and believes there are none higher than himself. Worship, you understand, it not just about going to church or praying or reading some ancient document and believing it to be somehow authoritative enough to warrant whatever sacrifices we make to it. Religion consists of the belief or beliefs we hold to as giving the answers to the ultimate questions we ask. The differences between worldviews lie chiefly in the answers they give to the more penetrating questions we ask of life. Everyone asks these questions sooner or later--but typically later, when some event or the anticipation of some event threatens our sense of well-being.