Ether Ch4-5

Just as the brother of Jared wasn't allowed to share his experience with everyone, Moroni is commanded to seal his writings so man cannot read, but it will be revealed when we have faith as the brother of Jared had. To do that, we must believe on the words of Christ and his disciples, repent, believe the gospel, and be baptized so we can be saved. Then Moroni warns to keep the sealed portion of the Golden Plates secret, and only show the Golden Plates to three who will be the witness for the rest of the world.
When Mosiah did his interpretation of the 24 plates of Ether, He kept the writings of the brother of Jared separate from the public records for the people because the Lord commanded him so save them for a day after Christ had appeared to his people (v1-2). Now that the Nephites have dwindled in unbelief and rejected the gospel they are hidden again not to be seen by the Gentiles until they are clean before the Lord (v3-6). There will be a day when we exercise faith in Christ and will be able to know those things that were manifested unto the brother of Jared, but those who contend against the word of the Lord will be cursed and will not be shown the marvelous works of the heaven (v7-10).
The believer of Christ's words will be visited by His Spirit and will know that they are true and that they are there to persuade men to do good just as the Father who sent Christ wants for all of us (v11-12). Christ wants the Gentiles to come to Him and ask for more precious knowledge that has been hidden because of the unbelief of many, and if we do, we will be blessed to know great and marvelous things out of the veil that keeps us in a state of wickedness (v13-15). When we have humbled ourselves enough to receive those truths we will know that the Fathers work has commenced on earth and all the ends of the earth will be called to repent, believe the gospel, be baptized, and blessed to God eventually being lifted up to dwell in His kingdom (v16-19).
Moroni is giving a small warning to Joseph to not translate the sealed portion of the book because God has forbidden it and only the privileged will be able to actually see the Golden Plates with their own eyes (v1-2). There are 3 that will stand as a witness in seeing the Golden Plates, and their testimony will stand against the world at the last day for those who believe and against those who do not (v3-4). All those who repent will receive the kingdom of God and those who believe it will see at the last day when they stand before God that the prophets have spoken truthfully (v5-6).