The common sense truth of religion is that part of what it is to be a human is to be always searching for God or a divine principle or wholeness. Whatever we wish to call God, we still look for it. The searching for God, the struggling with God is more important than having a particular faith as expressed by any of the world's religions. Of course, I do not advocate the renunciation of one's faith, but we should not think that because one person does not share the external trappings of our faith that that person is without a faith altogether and thus devoid of spirituality. The nature of humanity is such that no one is ever without a faith, a religion.
Religion is a universal reality which takes on many forms.
We can never escape it, try as we might. Natural science might cause us to doubt our religion, but it can only change the form of our religion, never rob us of it. By and through the doubts we have about our religion do we develop and perfect our religious ideas. It is tempting to adopt a position of religious relativism where all religions are equal and whatever religion you have is fine by me. This might be the best way to conduct interpersonal exchanges and get along with your fellows at the office, but it does not follow that all religions are equal just as it is not true that all theories are equally effective in accounting for phenomena.