simple-all of our "purposes" in our lives are to be ourselves-period. think about it. all of creation and universe follows both natural and universal laws. when you get this one, let me know.
energy and matter cannot be created nor destroyed, they can ONLY change form. thus, all there is, is transformation. ultimately, all there is, is life.
if there never has been another you, nor ever will be, your purpose is to be you-you cannot mess it up.
guess that means i trust creation/Creator/God/Universe, whatever makes sense to people. there is purpose in all "life" and creation. why teach that we are separate? we are not.
if your purpose feels you need to be in a religion, then thank you for doing that job! do it well. if you feel not to be led by religion, do yourself well.