Ignorance alone can never prevent survival; neither can confusional doubts nor fearful uncertainty.  When unbelievers question believers' knowledge of God, believers may respond to doubters, “How do you know that I do not know?”.  The believer has only one battle, and that is against doubt —unbelief. 
Do not fear; do not be troubled with doubts of failure or by perplexing confusion, do not falter and question your status and standing, for in every dark hour, at every crossroad in the forward struggle, the Spirit of Truth will always speak, saying, “This is the way”. 
The messengers who brought the news of the resurrection of Jesus believed what David had told them, and even those who somewhat doubted, carried the message just as certainly and just as swiftly.  Belief may not be able to resist doubt and withstand fear, but faith is always triumphant over doubting, for faith is both positive and living.  The first seven years of rebellion were times of heart searching.  But honest doubts and sincere questionings are not sin; such attitudes merely spell delay in the progressive journey toward perfection attainment.  Doubts inhibits free expression.  Doubts most stubbornly asserts itself just before crumbling.  Reference in 23rd Psalm: 
Whosoever has been born of the spirit has in himself the power to overcome all doubt, and this is the victory that overcomes all uncertainty, even your faith.  Temptation to doubt vanishes on 3rd circuit of Havona. 
John the Baptist swept aside all doubts about who was going to be and decided to start preaching.  Jesus experienced many seasons of uncertainty, if not actual doubt, regarding the nature of his mission. 
Thomas afflicted by doubts. The Master knew all about this and had an understanding sympathy for his apostle when he was thus afflicted with depression and harassed by doubts.  Jesus loved honest doubters.