It is important to remember that nowhere are we promised that the brokenness of this world -- the pain and crushing blows of the human condition -- will not break believers as well. We are, all of us, subject to the cruelty and ugliness found in this life (as well as its beauty and truth).
In the face of life's body-blows it is easy to doubt GOD's care (Jesus did), or even the Almighty's existence. This is OK, even normal, and presumably GOD can take.
Doubt is the natural flip-side of faith and both often reside in the same heart (they do in mine). Faith is a risk: "I might be wrong." The important question becomes therefore, is faith worth the risk?
Ultimately, faith is a matter of choice. In the face of the suffering all around me, and especially my own, will I believe in a reality behind the movement of the universe, or will I chose unbelief (which, remember is not the same thing as doubt)?