“For came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost.” (2 Pet. 1:19–21.) If we have that same power, then we ought to be able to understand .
So, prophecy does not have to be foreign and not understandable to us. If we have the Spirit with us, then the Spirit can help us to understand and know for ourselves of the truth of prophecy--since that prophecy came to the prophets by the same Spirit.
Now if we understand the words of Peter when he said, “We have also a more sure word of ” (2 Pet. 1:19), then in other words, there isn’t any other way in this world that we can know the mind and the will of the Lord as intelligently and assuredly as we can know it through the holy prophets. Then coming back to Amos, “Surely the Lord God will do nothing, but he revealeth his secret unto his servants the prophets.” (Amos 3:7.)
Prophecy is a gift to us to help us know what the Lord wants for His children. And we are able to open and enjoy that gift through prophets and the Spirit.