I don't believe that people die and come back as spirits, but I think there might be some unexplained events.
We will never fully explain the world by appealing to something outside it that must simply be accepted on faith, be it an unexplained God or an unexplained set of mathematical laws.
Big emotions that are unexplained are really scary. At least to me.
My feeling is that scientific method has the power to account for and interlink all phenomena in the universe, including its origin, using the laws of nature. But that still leaves the laws unexplained.
Everyone has a side to them that's kind of unexplained and feels misunderstood.