The first issue that is revealed by the tongue is envy.
From a Bible prospective, jealousy is the desire to protect what rightfully belongs to you, whereas envy is the desire to possess or destroy what rightfully belongs to another. Envy sees others who have, and rather than being motivated to earn it for themselves, causes them to simply want others diminished in what they have. Envy, when revealed in your heart, is an indication that you have removed your faith from being in God to being in possessions or position. The lust for these things has taken first place in your heart, and you believe that if you just had what that other person has, then you would be fulfilled or stable in life. In this fashion, envy is a tell that your faith has been misplaced and can be a central reason for instability in your life. I will address this in much greater detail in the next chapter.
The second issue revealed by the tongue is that of strife.
A person can simply be a contentious person filled with strife in their heart and as a result they drive away relationships and destroy institutions. Many homes, churches, and work places are destroyed by someone who simply has a contentious spirit of strife in them. A person with this attitude will not let anything go, they seemingly must be right which often puts them in conflict with others. They argue about everything and feel the desperate need to correct everyone else.
One thing I notice is that we are told in the first verse of chapter three, “be not many masters”. This means we should not be trying to teach everyone else. This can be a characteristic of those on an emotional upswing, at those times they can think they know everything and are going to show everyone else how it’s done. This is an indication of someone who has also removed their faith from being in God and has set it in themselves. They are filled with the pride of their own person. No one is always right, no one knows everything, but the person who is filled with strife thinks that they might, though they say differently that is exactly what their actions and attitude show. They feel that they have not only the right but the responsibility to correct others when they perceive them to be wrong. This strife ultimately causes them to feel isolated and because others will not confirm their beliefs it sets them up for a big letdown.