Moroni declares emphatically that since God is “the same yesterday, today and forever,” then a willingness to perform miracles is still a foundational part of God’s character. Mormons believe that the ancient prophet is here speaking to a modern culture that would be prone to denying miracles; if people aren’t seeing miracles in the modern world, Moroni places the blame squarely on their own shoulders because they lack faith.
Remember that the Book of Mormon came forth at the close of the Enlightenment, or Age of Reason, when many people believed that science and empirical knowledge could be depended upon to fully explain the workings of the universe. Seeing into the future, Moroni speaks to these people directly by proclaiming that the God of Abraham, Isaac, and Jacob is still a God of miracles. (Skeptics and critics of the Book of Mormon, of course, point to this same passage as evidence that Joseph Smith wrote the book, since it so clearly refers to the intellectual conflicts of the early nineteenth century.)