“The Book of Mormon teaches that God will manifest the truth of spiritual things unto us by the power of the Holy Ghost (see Moroni 10:4–5). In modern revelation God promises us that we will receive ‘knowledge’ by His telling us in our mind and in our heart ‘by the Holy Ghost’ (D&C 8:1–2).
“One of the greatest things about our Heavenly Father’s plan for His children is that each of us can know the truth of that plan for ourselves. That revealed knowledge does not come from books, from scientific proof, or from intellectual pondering. As with the Apostle Peter, we can receive that knowledge directly from our Heavenly Father through the witness of the Holy Ghost” (Oaks, “Testimony,” 26).