—Deuteronomy 18:20-22 (NASB)
There are two basic flavors of false prophets—those who claim spiritual insight, knowledge, and power through some entity other than the One True God, and those who falsely claim such as coming in His name. One attempts to exalt a false god to overtake the place of God, the other to exalt themselves in His place. In either case, the defining biblical characteristic is that they speak "presumptuously".
The root of this word is "to boil" or "to seethe". It describes someone who is acting out of uncontrolled pride and rebellion with a dash of arrogance. At their core, false prophets are people who have issues of unresolved and misaddressed pride and anger so that they seek to set aside the authority over them. They're engaged in a personal battle fueled by their raging pride to place themselves higher than the object of their anger. It's somewhat ironic that at the center of their being they are angry with and rebelling against God, but often disguise their actions in His name to hide this conflict of interest.
This does not mean that every person that is overly passionate or emotional is a false prophet. The test is not according to feelings or visible affectations but according to their message, whether he "speaks in the name of other gods" or something "in the name of the Lord…which the Lord has not spoken". We are not to allow our eyes to distract our ears and will know the difference if we stick to evaluating their words.
You see, it does not matter whether or not people are being healed by Benny Hinn; he is a false prophet because of the many times the things he's spoken have not come true. He is betrayed by his words. I know that there are ongoing investigations into him and others to determine if the signs and wonders claimed to have been done in Christ's name are real or not, but that's not the actual test—it's whether or not the message which accompanies their works is the Truth and nothing but God's Truth.†††