Peace can be threatening because peace is the absence of problems and conflict. There is something, perhaps in the personal you, that does not want freedom or peace, or the absence of problems. There's something that wants the opposite.
Peace can be threatening ...
Quotes from the same author
Not until you surrender does the spiritual dimension become a living reality in your life. When you do, the energy you emanate and that then runs your life is of a much higher vibrational frequency than the mind energy that still runs the world.
Through the present moment, you have access to the power of life itself, that which has traditionally been called "God." As soon as you turn away from it, God ceases to be a reality in your life, and all you are left with is the mental concept of God, which some people believe in and others deny. Even belief in God is only a poor substitute for the living reality of God manifesting every moment of your life.
The mental suffering you create is always some form of non-acceptance, some form of unconscious resistance to what is. On the level of thought, the resistance is some form of judgement. The intensity of the suffering depends on the degree of resistance to the present moment.
The greatest achievement of humanity is not its works of art, science, or technology, but the recognition of its own dysfunction.
You cannot find yourself by going into the past. You can find yourself by coming into the present.