Friends:

   How to cure the hesitant & vacillating Doubt-&-Uncertainty!

Noticing Doubt-&-Uncertainty (vicikicchā) emerges can make this suspense fade away:
Herein, Bhikkhus, when Doubt-&-Uncertainty is present in him, the bhikkhu notes & understands:
There is Doubt-&-Uncertainty in me, & when Doubt-&-Uncertainty is absent, he notes & understands:
No Doubt-&-Uncertainty is in me. He also understands how unarisen Doubt-&-Uncertainty arises.
He understands how to leave behind any arisen Doubt-&-Uncertainty, and he understands how left
Doubt-&-Uncertainty will not arise again in the future.                                               MN 10

What is the feeding cause that makes Doubt-&-Uncertainty arise?
There are doubtful, indeterminable, & inconclusive ambiguities! Often giving irrational & unwise
attention to such matters, is the feeding cause of the arising of unarisen Doubt-&-Uncertainty, &
the feeding cause of worsening and aggravation of Doubt-&-Uncertainty, that already has arisen.                                                                                                                                                           SN 46:51
What is the starving cause that makes Doubt-&-Uncertainty cease?
There are advantageous & detrimental states, blameable & blameless, average & excellent states,
and dark & bright states, frequently giving rational & wise attention to these, is the starving cause
for the non-arising of unarisen Doubt-&-Uncertainty, & the starving cause for the resolute clearing
of Doubt-&-Uncertainty, that has already appeared.                                                   SN 46:51
                                                                                                                                        
Some advantageous reflections to return to whenever Doubt-&-Uncertainty sneaks in:
There are these 6 things, which help to throw out doubt:
1: The state of being learned in the Buddha-Dhamma.
2: Examining the Buddha, Dhamma, and Sangha.
3: Understanding the advance of Moral Discipline. 
4: Being decided & convinced about the 3 Jewels.
5: Sympathetic, clever and helpful friends, who knows directly. 6: Explaining talk that dispels doubt.

Doubt-&-Uncertainty is like a Desert:
Doubt-&-Uncertainty is just as when a rich man travels through a desolate desert where there is no
food and much danger. Freedom from Doubt-&-Uncertainty is like when he has crossed the desert,
and gradually reaches safety near a village, a secure place, free from danger. The he is relieved.
                                                                                                                                              DN 2

It is exactly & even so with one in whom doubts about one of the 8 objects of doubt# has arisen.
Doubting whether the Master really is a perfectly Enlightened One or not, he cannot become
assured of it with confidence. Unconvinced he remains unable to attain to the paths and fruits
of Nobility. Thus, as the traveller in the desert is uncertain whether robbers are there or not,
he produces in his mind, again and again, a state of wavering and vacillation, a lack of decision,
a state of anxiety; and thus he creates in himself an obstacle for reaching the safe ground of
the Noble Ones (ariya-bhumi). In that way, sceptical doubt is like travelling in a desert.

#: They are, according to the Vibhanga: doubt in regard to the Buddha, the Dhamma, the Sangha,
the (threefold) training, the past, the future, both past and future, and the conditionality of
dependently arisen phenomena .

The Buddha was once questioned by an elderly yet undecided and divided brahman Dhotaka:

I see here in the world of beings divine & human, good ones, who lives possessing nothing. I thus bow for you All-around Eye. Please Sakyan, release me from my doubts!	The Buddha answered: No one in the world, Dhotaka, can I release from doubting. But knowing the most excellent Dhamma, you will cross the ocean of uncertainty.
Dhotaka now more confident: And I admire, Great Seer, that peace supreme, all stilled, knowing which, living aware and detached, I'll go beyond the entanglement of this world.	Then I will teach you that peace even right here & now, not just hearsay words, understanding which, living aware and detached, you'll go beyond the entanglement of this world.
Teach me as your friend, O best one, the Dhamma of detachment so that I may know directly so that I, as unaffected as space, may live right here, at ease in peace. calmed and not dependent...	Whatever you are aware of, Dhotaka, above, below, across, or in between; know this as a chain to this world! Thus, do not create any craving for any being, becoming or non-becoming. Sutta Nipata V 6

See also:
http://What-Buddha-Said.net/drops/Barren_Stagnation.htm
http://What-Buddha-Said.net/drops/IV/Suitable_Substitution.htm
http://What-Buddha-Said.net/drops/II/Doubt_and_Uncertainty.htm
http://What-Buddha-Said.net/drops/II/How_to_Overcome_Doubt.htm