This is one of the most courageous and challenging messages in the entire Book of Mormon. Moroni invites any person who has an opportunity to read this divinely-preserved record to carefully ponder its contents. It contains a sacred message and Moroni invites the reader to test its truthfulness by asking God to verify its divinity by a direct revelation.
He promises the reader that if he or she will sincerely study the Book of Mormon and ask the Father in the name of Jesus Christ whether or not it is true, the Father will manifest the truth of it by the power of the Holy Ghost. Moroni wants us to know that the Book of Mormon is a second witness that Jesus is indeed the Christ.
Hundreds of thousands of modern Lamanites and Gentiles have asked the Father whether or not the Book of Mormon is true and they have received the absolute conviction, confirmed by the Holy Ghost, that it is indeed true and therefore Moroni's promise has been literally fulfilled as they have received a divine testimony of this great book.