Carl Jung: Fanaticism is ever the brother of doubt,

Has it ever—except in the most benighted periods of history—been observed that a scientific truth needed to be elevated to the rank of a dogma? Truth can stand on its own feet, only shaky opinions require the support of dogmatization. Fanaticism is ever the brother of doubt, ~Carl Jung, CW 10, Para 335

Doubt and insecurity are indispensable components of a complete life. ~Carl Jung, Letters Vol. II, Pages 163-174

Doubt is the crown of life because truth and error come together. Doubt is living, truth is sometimes death and stagnation. ~Carl Jung, Dream Analysis, Page 89.

When you are in doubt you have the greatest opportunity to unite the dark and light sides of life. ~Carl Jung, Dream Analysis, Page 89.

He who cannot bear doubt does not bear himself. Such a one is doubtful; he does not grow and hence he does not live. Doubt is the sign of the strongest and the weakest. The strong have doubt, but doubt has the weak. ~Carl Jung, The Red Book, Page 301.

I do not doubt: I also want evil for the sake of my God. I enter the unequal battle, since it is always unequal and without doubt a lost cause. How terrible and despairing would this battle be otherwise? But precisely this is how it should and will be. ~Carl Jung, Liber Novus, Page 289.

But fanaticism is always a compensation for hidden doubt. Religious persecutions occur only where heresy is a menace. ~Carl Jung, Analytical Psychology and Education, Page 81.

Fanaticism is due to an unconscious doubt threatening the conscious attitude. For example, dogmatism is merely to protect a creed against an unrecognized doubt. True conviction needs nothing of the sort. Fanaticism is due to a threatened conviction. ~Carl Jung, Cornwall Seminar, Page 18.

Doubt is creative if it is answered by deeds, and so is neurosis if it exonerates itself as having been a phase—a crisis which is pathological only when chronic. Carl Jung, Letters Vol. 1, Pages 332-334

Neurosis is a justified doubt in oneself and continually poses the ultimate question of trust in man and in God. Carl Jung, Letters Vol. 1, Pages 332-334

I for my part prefer the precious gift of doubt, for the reason that it does not violate the virginity of things beyond our ken. ~Carl Jung, Psychology and Alchemy, Page 8.

I am just as much in doubt about myself as before, the more so the more I try to say something definite. It is as though familiarity with oneself alienated one from oneself still further. ~Carl Jung, Letters Vol. II, Pages 162-163.

Carl Jung: Doubt is justified only where it is a question of a deliberate lie.

The psychologist is little concerned here with what kind of facts can be established in the conventional sense; all that matters to him is whether a person will vouch for the authenticity of his experience regardless of all interpretations.

The reports leave no doubt about this; moreover in most cases their authenticity is confirmed not only by the freedom with which they were reported, but also by independent parallel stories.

Since it cannot be doubted that such reports are found at all times and places, there is no sufficient reason for doubting the veracity of individual reports.

Doubt is justified only where it is a question of a deliberate lie.

The number of such cases is increasingly small, for the authors of such falsifications are too ignorant to be able to lie properly. Aniela Jaffe, Apparitions and Precognitions, Pages vii – viii.