It is basically based upon pride. Well, as many of us know, there are many things under heaven and earth that we know do exist which cannot be measured and seen, yet we know with certainty they are real. Your body weighs exactly the same amount before death as after death. A huge change has taken place when you die, but you cannot measure what was lost. This is because your soul has left but did not have any material weight to take with it.
Science is based upon finding the correct tools to measure the correct object.
For instance you cannot use a stethoscope on a tree, it is meant to measure humans. Well, show me a tool that can measure something that has no matter or substance. There is no such thing. Well, in the same way, modern science does not even have a tool to examine the spiritual world. The fact that they cannot provide proof does not show that God does not exist, it just shows that science is not the tool to find out.