How can I explain soullessness to other one? One of my friend don't accept Buddhism theory of soullessness.She is also buddhist.So my question is how can I explain the soullessness to her?
Both soul exists and soul does not exist are extreme view:


  Ananda, if I — being asked by Vacchagotta the wanderer if there is a self — were to answer that there is a self, that would be conforming with those brahmans &amp; contemplatives who are exponents of eternalism [the view that there is an eternal, unchanging soul]. If I — being asked by Vacchagotta the wanderer if there is no self — were to answer that there is no self, that would be conforming with those brahmans &amp; contemplatives who are exponents of annihilationism [the view that death is the annihilation of consciousness]. If I — being asked by Vacchagotta the wanderer if there is a self — were to answer that there is a self, would that be in keeping with the arising of knowledge that all phenomena are not-self?


Ananda Sutta

Simply there is nothing worthy of identifying as self, because you are not in control, whatever you identify as self are not entirely pleasant.