Jacques Ellul once wrote,
The person who is plunged into doubt is not the unbeliever, but the person who has no other hope but hope.
Actually, an unbeliever doesn’t have to wrestle with doubt unless they doubt their unbelief! You can’t really doubt something you don’t believe in the first place. However, believers can easily fall into doubt because even while we believe in God, we don’t actually have all the proof. We’re living “by what we believe, not by what we see” (2 Corinthians 5:7).
If you believe, if you have faith, then you will always be susceptible to doubt.
Stop believing and you’ll stop doubting.
Stop believing and you won’t see any need to question God.