Discerning love of self and love of the world vs. love of the Lord and love of the neighbor is not all that difficult. That's what evil and falsities vs. goodness and truth boil down to, isn't it?
It's always good to realize when we are following the Lord's path and doing His will.
I am not speaking about knowing whether the Spirit is a driving force in one's life. I am refering to particulars of your faith - the content of Scripture and critical questions of the faith, such as "who is God?". The answers to these questions do not come from within, as Mormonism proclaims (the so-called "burning of the bosom"). How do you know you are not delusional regarding such matters?
Regards