I cannot find anything that backs up your claim that science is the only way of knowing truth. I ask you, what science has been done to show that this statement is true - that only science can show us the truth?
So far science is the only method with which we can prove hypotheses made from observations. Some times we find that the hypothesis is incorrect so then we find other observations and correct the conclusions and it becomes a theory we then keep finding better ways to observe and adjust the theory until the truth is found, (for example the early hypothesis of the earth rotating about the sun, which is now a fact). No such methodology has been successful to establish any kind of the supernatural, although many have unsuccessfully tried to do that, but the claimed “successes” have not been repeatable and are not accepted by the great majority of the scientist in these fields. That means that the hypothesis that there is a supernatural realm, is just a unproven speculation. If you know any better way to do this kind of investigation I and many others, including scientist, will gladly receive your non-science based method, if you can think of one, that make sense.