Word for someone who starts to question his faith?

I'm reading a book about a boy who starts to question the existence of God. He believes He's there but he has no proof so he starts to question if He really exists.

Solution 1:

The most obvious one that comes to my mind would be skeptical.

Skeptical : having or expressing doubt about something (such as a claim or statement) http://www.merriam-webster.com/dictionary/skeptical

Other words that might fit are inquisitive, doubting, or questioning.

Solution 2:

I like ambivalent:

ADJECTIVE

Having mixed feelings or contradictory ideas about something or someone:

We all live our lives on a foundation of faith. Some have faith in science, nature, mankind, or themselves. Others have faith in a transcendent God. As long as we can squeeze all of the evidence and outcomes into our "faith box", we are confident, but let a defining crisis push us out of that box, and suddenly we are plagued with doubts about everything we have believed. Conversion, whether to or from faith in God, always begins with ambivalence.

Voltaire said:

“Doubt is an uncomfortable condition, but certainty is a ridiculous one.”

René Descartes concurred:

“If you would be a real seeker after truth, it is necessary that at least once in your life you doubt, as far as possible, all things.”

Paul Tillich, a religious man agreed:

“Doubt isn't the opposite of faith; it is an element of faith.”

Ambivalence, forces us to enlarge our frame of reference to explore the powerful poles of reality that confuse our thinking:

"simultaneous conflicting feelings," 1924 (1912 as ambivalency),

from German Ambivalenz, coined 1910 by Swiss psychologist Eugen Bleuler (1857-1939) on model of German Equivalenz "equivalence," etc.,

from Latin ambi- "both" (see ambi-) + valentia "strength," from present participle of valere "be strong" (see valiant). A psychological term that by 1929 had taken on a broader literary and general sense.

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