Thinking, or more precisely identification with thinking, gives rise to and maintains the ego, which, in our Western society in particular, is out of control. It believes it is real and tries hard to maintain its supremacy. Negative states of mind, such as anger, resentment, fear, envy, and jealousy, are products of the ego.
The psychological condition of fear is divorced from any concrete and true immediate danger. It comes in many forms: unease, worry, anxiety, nervousness, tension, dread, phobia, and so on. This kind of psychological fear is always of something that might happen, not of something that is happening now.
A great deal of what people say, think, or do is actually motivate by fear, which of course is always linked with having your focus on the future and being out of touch with the Now. As there are no problems in the Now, there is no fear either.
Let the end of the world be inside you, then you don't need to fear the end of the world out there.
Internal and external are ultimately one. When you no longer perceive the world as hostile, there is no more fear, and when there is no more fear, you think, speak and act differently. Love and compassion arise, and they affect the world.
Fear arises through identification with form, whether it be a material possession, a physical body, a social role, a self-image, a thought, or an emotion. It arises through unawareness of the formless inner dimension of consciousness or spirit, which is the essence of who you are. You are trapped in object consciousness, unaware of the dimension of inner space which alone is true freedom.