Just what is the role of the modern prophet? Do they receive new "revelation"? Is the Bible canon closed? Just how should the modern prophet view the messages they discern? In the Old Testament prophets served as the communication link between the people and God. Beware of any who offer secret knowledge, who offer to validate your relationship with God, or who do not use scripture as the basis for anything they share.
Remember the words of 2 Peter 1:20-21: "...no prophecy of the scriptures is of any private interpretation. For the prophecy that came in older times, not by the will of Man; but holy ones of God spoke as they were moved by the Holy Ghost." (Note the KJV uses "men" but the Greek uses the word for "humans" inferring that the prophecy was spoken by either man or woman.).
How do we identify "false prophets"? Without a standard it is hard to prove a prophet false and that is what con artists over the centuries have used to their advantage. When people have "itching ears" and only want to hear what they want to hear it becomes easy to manipulate them. Peter stresses that just as in the old days there were "false prophets" there would also come in the new faith, "false teachers". Even as the new faith was being crafted in the New Testament, Peter to "stir up your pure minds by way of remembrance: That ye be mindful og the words which were spoken before by the holy prophets...."(2Peter3). Jesus warned of falseness in Matthew 24:24: "...there shall arise false Christs, and false prophets, and shall show great signs and wonders...if it were possible they shall deceive the very elect." "For many deceivers are entered into the world...." 2 John 1: 7-9. How can a person determine the truth? That is the role of scripture.
"Beloved follow not that which is evil, but that whis is good. He that doeth good is of God...but he that doeth evil hath not seen God." 3 John 1:11 How to tell? "Believe not every spirit, but try the spirits whether they are of God: because many false prophets are gone out into the world." 1 John 4: 1-5.
The Bible provides the standard, the balance, the means of saying 'is this prophet of God?' It requires, however, that the people know the "Book". False prophets arise where there is no longer knowledge of the message of God. They present themselves as the replacement for the book, they have the new revelation, the new message, and the only truth. They become the mouthpiece of god - but perhaps not the God of the scriptures.