Moroni presents evidence of the faith of New World prophets, a list similar to events recorded in Mormon’s text. Although similar events may have been unrecorded, an earthquake that destroyed prison walls occurred to Alma and Amulek (Alma 14:27), while the combination of a fiery furnace and wild beasts was attributed twice to the Three Nephites (3 Ne. 21:22, 4 Ne. 1:32–33).
There is no referent for the poisonous serpents (though the idea parallels Mark 16:18, a reference that will be even more explicit in Mormon 9:24). Moving a mountain is recorded only once in the Book of Mormon. It appears in Ether 12:30 in a passing comment by Moroni that is out of chronological order. Thus, by the time Moroni wrote this sentence, he had read the book of Ether.
Moroni’s point about the fathers is that their faith could make marvelous things happen. Therefore, their faithful prayers “in behalf of their brethren” will surely come to pass. He returns to this theme in verse 26.