What is the root cause of fear?

1) From dislike (dwesh) -> scorn (tiraskar) -> fear

If a man dislikes his wife, he will see many mistakes in her and will harp on her negative points. This constant faultfinding leads to scorn (tiraskar). The scorn leads to fear. He will experience fear in certain interactions with her and when he sees her, he feels a sense of suffocation and uneasiness. We all tend to be afraid of those or that which we dislike intensely. All this is a result of scorn. In order to break free from this feeling of contempt, one has to keep asking for forgiveness. Even though the other person may not be aware of it, you have to continue asking for forgiveness from within.

2) Attain Perfection Through Abstinence From Retaliation

In this world, any person that harms you in any way is simply an 'instrument'. You are responsible because you suffer the damage. In reality, this world is truly independent and no one can interfere with another. And if this were not so, there would be no end to people's fear and no one would achieve liberation. Even Lord Mahavir would not have attained liberation. Lord Mahavir was completely impervious to any feelings projected towards him by others. People's feelings towards him ranged from reverence to contempt; from love to sexual desire; from respect to insult. Nothing affected him. There was no element of retaliation in him to anything. The one who is free from retaliation attains final liberation. The one who retaliates has to stay behind to suffer the consequences.

The world will go on binding you with all sorts of negative and positive feelings. If a pickpocket sees you putting money in your pocket at a train station, would he not make the intent to steal it? And suppose you were to suddenly board the train as it was pulling away, leaving the pickpocket behind, even though he missed the opportunity to steal your money, he still formulated the intent to steal and this will bind him for new karma effects.
Everyone in the world is going to have such positive or negative inner intent but if there is no retaliation from you then you will be left alone. If you do not put your own intent in others' intent, no one in the world can bind you; otherwise there would be no end to it.