There is wrong that is being done, and it is all with harm. But there is not agreement on what is wrong, that harm comes from. God still knows what is wrong. But people do not all know, you even would not know all that is wrong. If you are shown harm from some things that you would not see as wrong you would just say you do not see harm in those things. People are all like that. So it happens that we do need God to tell us things.
And how does that happen? Most people have one of two answers, both of which are insufficient. The first is that they know someone who is a prophet who speaks for God. But how can they verify that? There are a gazillion wannabe prophets who all say different things. The other is similar, that some prophet wrote a sacred text. Again, the pertinent question would be how to know which religious text is the "right one" since they all contradict each other.
Yes, many are such that are false in giving prophecy. At the time there were those who could be put to death, for saying that God said such that they speak, and those things do not turn out to be true. That things did happen as were claimed in prophecies showed that such giving those were true, and further prophecies were kept, even when such prophets had already been killed. And now there are scripture texts with many prophecies that are fulfilled, and what is revealed from prophets as these has weight of authority. It did not come so easily. You may think of some contradiction, we can look at those.