A lesson on bitterness
I don't think he meant that you shouldn't feel anger. I think he meant not to let it turn to bitterness that lingers on forever and keeps you captive.
I'm actually not bitter. Sometimes I get angry but anger motivates me to change something in my life. There are so many ways to screw up your life or have it screwed up for you by your parents, this cult is just one of them.
I don't think that bitterness is the problem. The problem is when your own enemy re defines your motivation to fight back as bitterness and points everyone else arounds you to see it as a defect. All of these quotes that are thrown around on the internet have an enormous amount of truth in them. The problem is they are also abused with the purpose of manipulating others. Picture the following...
Scenario 1) Nelson Mandela walks out free and as he does, he flips the bird to everyone at the jail. While this is a bit of an exaggeration, this is what I would define as bitterness. Simply because it does nothing for your cause. They probably deserved the bird but it does not free all of the others that suffered his same fate.
Scenario 2) Nelson Mandela walks out free and as he does, he smiles and tells everyone in the jail, including his guards and captors that he loves them and that they don't really know what they are being forced to do. He also adds that he will spread the word of truth so that no one has to suffer the same fate as he did. All out of pure concern for fellow humans. Upon finding this out, his captors follow right behind him telling every eye witness, that he is doing this out of bitterness. Telling them that to imitate his attitude would result on them suffering the same fate. Telling everyone not to listen to him because what happened to him was his own fault and that he was free to leave whenever he wanted to and no one held a gun to his head to make him stay.
The second scenario is the closest thing to the WTBTS and the very definition of a bully. I know also because my 11 year old daughter is going thru this at school at this very moment.