Doubt is the act of considering the possibility that a belief may be wrong. Since religion is based on far fetched principles that often have little evidence or are contrary to everyday experiences, it is normal to doubt theistic dogma.
"There are moments, sure, where you think 'Is there a God? Where is God?' [...] Yes. I do [doubt]. In lots of different ways really. [...] I love the Psalms, if you look at Psalm 88 , that's full of doubt."
- — Justin Welby, Archbishop of Canterbury
- "I suddenly faced the possibility that the beauty I saw in the Christian religion and my perception of God was just beauty, like carefully crafted art, or carefully crafted words. Maybe beauty was all it was. Like a poem or a story, that was deeply touching, but not true. "
Doubt about the existence of God is experienced by the majority of Christianity outside of evangelical denominations. Doubt also occurs within Islam but is a minority view.  Many believers manage to reconcile recurring doubts with their beliefs. 
While many Christians and Muslims think that doubt is to be discouraged, doubt is used by many intellectual disciplines to great advantage. Systematic intellectual doubt is referred to as skepticism.
"But whoever has doubts is condemned if he eats, because the eating is not from faith. For whatever does not proceed from faith is sin."
"But let him ask in faith, with no doubting, for the one who doubts is like a wave of the sea that is driven and tossed by the wind."
Doubt and sin
Some evangelical preachers claim that doubt is sin:
- "You’re going to have to settle it in yourself, that doubt is sin. It’s sin. Until you realize that doubt is sin, the devil will keep you doubting God’s promises and God’s Word, and your prayers will go unanswered and they will not be fulfilled. "
However, more Christians accept that some doubts are normal and perhaps necessary as a step to a deeper understanding of God. 
- If God exists and he is a good father figure, he probably feels sympathy for his creations having honest doubts. It makes little sense that would punish doubt.
- A God that would punish his creations for having doubts is unworthy of worship.
Responses to doubt
A frequent recommendation for those experiencing doubts is to speak to other supportive Christians.  One might add the recommendation to talk to anyone who is supportive, including atheists and those of other faiths.
Reading holy scriptures is also thought to strengthen faith. 
Some answers are arguably not resolved until people reach heaven. However, how the believer knows this to be true can be a subject of doubt.
- "the answers will not come until we get to heaven "
Some apologists insist that since God exists and always speaks the truth, there is no need for doubt.  This response assumes the existence and attributes of the very thing that is the subject of doubt. It is therefore a ciruclar argument.
If doubts are on a non-essential Chrisitan doctrine, apologists advise that doubts should be put in perspective and not exaggerated. 
Apologists point out that a simplistic understanding of Christianity is open to many objections but a deeper understanding is not subject to these arguments. 
- Main Article: Advice on deconverting
"Let us SPEAK [...] though it be bad. To be silent is worse; all suppressed truths become poisonous."
- Read widely. People have been questioning religion for thousands of years and it can save you a great deal of time. 
- Ask yourself if your values are different or even superior to your current religion.
- Does your religion oppress you or other people?
- Question if the doctrines of your religion make sense. Understand both sides of the argument.
- ↑ Chris Redford/Evid3nc3, Deconversion: Personal Relationship (Part 2), 29 Dec 2009 
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- ↑ 4.0 4.1 
- ↑ 5.0 5.1 5.2 5.3 
- ↑ 6.0 6.1 Tracie and Matt Help a Doubting Christian, Atheist Experience 2014-03-02
- ↑ 7.0 7.1 7.2 
- ↑