Jesus spoke many parables to teach us the way to live good lives. There were also many prophecies about Him and the most famous being His death and resurrection. According to the Bible, Prophets of the Old Testament relayed prophecies from God. Many cultures and religions have their source of prophecies to guide in a good path.
Of course prophecies can be positive or negative, depending on who is speaking it, what their motive is and where they got their source of information from?
As to be believing in prophecy in this age, I think we should seek the face of the Lord and pray for guidance.