I have never doubted the existence of God, but have often questioned His character, as portrayed by Christian beliefs. People like to tell themselves that His every thought and action is done with the betterment of mankind in mind. But if you read the Old Testament, you discover that this is not always the case; many of His actions...many downright cruel...we're for His own self-glorification. This is not bashing the Lord, but it is true; and anyone who denies that is delusional.
While the Lord IS good, there are other questionable aspects of His character that we cannot, and are not meant to ever understand. I am finding that out the hard way.
As difficult as it is at times, because His ways are greater than ours, we have to try to believe that the things He allows (even the horrific things), have some sort of significance. Even if we don't agree with or understand what that significance is.