Self ownership

In the class we seem to come to the conclusion that, if one tries hard enough and if one really wants to then one can achieve a rational argument, separate from the theology as to why one cannot commit suicide. However I am not completely convinced that this is so.Which made me wonder exactly how much of the rest of Locke's theory would be affected if, this particular section of killing one's self and others could not be entangled from the theological. Are there a parts that directly need this section to be true? or can one still continue with the theory of property without and clashing?