Many Christians, like the Sadducees of Jesus' time, do not believe in the supernatural, and they try to find some explanation for everything that looks beyond the natural. On the other hand, many Christians who believe in the almighty God who intervenes miraculously in human lives jump to conclude that something must be from God if it is supernatural! It is sad to be led astray by the Devil while we are thinking God is leading us in special ways.
What would you do if you had a 'visitation' from Jesus or an angel proclaiming the word of God who told you about some special task you were called to accomplish? You would naturally be greatly thrilled at this experience and you may become willing to do anything you are told. But would you still take care to examine what you are told with the word of God to see if you are really hearing from God or a deceiver? Or would you assume that your experience must be genuine because it is Jesus you saw or the angel was quoting from the Bible?
Jesus warned us about deception attacking children of God especially in the 'last days' (Mt.24:24). Most times it doesn't look like deception because it comes to us 'in the name of Jesus' (vv.4,5) or using the words of God. Paul warned about deception from Satan when he disguises himself as an 'angel of light' proclaiming what seems like 'light' from God (2Co.11:14).
There are books written by people who were listening supposedly to the direct words of God as they humbly waited on Him. Many of those words appear to be encouraging and comforting, but the deception is in what is not written. The picture we get after reading such books is of a very 'nice', lovable God. Without any mention of God asking us to repent from our sins and learn to walk rightly before Him, the picture is a deceitful caricature of the real God.
Suppose you got a vision or dream telling you about the great plans God has for you which makes you feel somewhat superior to the 'ordinary' Christians and you neglect to consult anyone else or God's word to see what you are supposed to do, isn't that a way to ultimate ruin? So many people who sincerely thought God was directing them have finally destroyed themselves in this way.
As you read the Bible and you suddenly get a bright idea, is it something for the next sermon, a bestseller you are to write or a new movement you are to start? Such bright ideas came to Jesus too in the desert. But He was watchful against temptation because He knew the Father's words, His own humanness, the existence of the Deceiver and the history of others who had fallen. So He told His disciples to watch and pray at all times (Mt.26:41).
God does do many supernatural things. But everything supernatural does not come from Him. He wants us to check things with His written word which He has given to us as a standard and a benchmark against which we can calibrate everything else. If we get fooled we may hurt many more people than just ourselves.