There is a difference between doubt, skepticism, and outright unbelief.
Skepticism is when someone „can’t believe” and unbelief is when someone „won’t believe.”
Skepticism is honesty, while unbelief is stubbornness.
Skepticism is looking for light, and unbelief is being content with darkness.
Doubt Your Doubts and Believe Your Beliefs
(Greg Laurie – The Christian Post)