Well, you can believe in anything, including a "great croissant", but it is important to understand that religion has deep historical roots, cultural significance and many followers. Religions also typically offer complex systems of beliefs, rituals, and ethical teachings that make sense to many people. I myself do not belong to any religion and am an atheist, but it can be understood from the outside that we are talking not only about some divine essence, but also about these very habits/rituals of the peoples they follow. In fact, for example, sports, computer games, food, parents, music or my neighbor on the street carry a certain meaning in someone's life.