What did James mean when he said that the tongue “defileth the whole body,” “setteth on fire the course of nature; and it is set on fire of hell [gehenna]”? Is this a reference to eternal punishment?

Gehenna, also known as the Valley of Hinnom, was once the garbage dump of the city of Jerusalem located just outside its walls to the southwest in a deep, narrow valley. It was also the place where the bodies of executed criminals denied a burial, were disposed of. Fires were kept in a constant state of burning there to destroy the rubbish and the bodies and minimize the awful smell. This explains why it was called an “everlasting fire”; and whatever the flames didn't devour, the maggots took care of. This explains the place of “hell fire” mentioned in Mark 9:43-48. 

Gehenna is not another name for the imaginary fiery hell of religious tradition… The mistake that religious teachers in general always make upon seeing the word “judgment” in Matthew 5:22 and other verses similar to it, is that they think this judgment is the one that follows death. It is not that judgment. The judgment in Matthew 5:22 simply refers to the temporal judicial process that was in place in the days of the apostles, to punish convicted lawbreakers. and also to the judicial process that will exist in the theocratic Millennial Kingdom, but it still won’t have anything to do with the judgment that occurs beyond death.

You will not be judged and thrown into Gehenna even if you are guilty of these things because:

1. Gehenna is a physical, not spiritual place, and was formerly the garbage dump located outside the old city walls of Jerusalem. Today it is a beautiful garden. 

2. You are not living under the Millennial Kingdom that doesn’t yet exist in Jerusalem.

3. The judgments handed out in connection with Gehenna have to do with Jewish citizens appearing physically and still alive in their natural bodies in the court of Christ’s Millennial Kingdom.

4. The judges of that court shall be the twelve apostles (Matthew 19:28; Luke 22:30).

5. The citizenship of believers today is in heaven not in Jerusalem.   “For our conversation [citizenship] is in heaven; from whence also we look for the Saviour, the Lord Jesus Christ” (Philippians 3:20)

You can safely remove the Gehenna warning light — installed by religious tradition — from your spiritual alarm panel. It doesn't belong there.