Complaining against God occurs mostly with people who are haughty or foolish.
Whatever might happen to us does not happen without God’s permission, as said by the Righteous Job: as it seemed good to the Lord, so has it come to pass (Job 1:21). And therefore like him we must endure unpleasant experiences in life and restrain ourselves from complaining, and not say: “Why is it this way, and not that way?”
St. Anthony of Optina