Maybe Satan doesn't exist and the human condition is perfect and we don't need to fret about such things or resist a sophisticated cult organization concealing itself as Christianity, or help our fellow Christians that may lack perfect knowledge.
He does exist which is exactly why Christians need to be better educated on their faith. For example: They need to know why the LDS’ Father, Son and Holy Spirit are not the same as what orthodox Christians believe on the Trinity.
A Christian should not only know the right answers he or she should also know the right questions. Such as asking where in Scripture the idea that Father God has a physical body or that Lucifer and Jesus are Spirit Brothers. Mind you they will do some Scriptural gymnastics to prove this so you must be ready to counter with the whole Nature of God etc, etc apologetic vs the nature of the created angel. Oh and the whole rebellion bit too.