God is not the author of sin. He never condones, causes or excuses sin. However, at times, He does allow His children to experience the consequences of another's sinful actions. Moses took the brunt of the Isrealites' selfish and rebellious actions. The fact that he had experiences harsh treatment...did not excuse his responsibility to trust the sovereignty of God. Although God allows people to act contrary to His will, He promises that nothing will ever happen to you contrary to his will.
"Your greatest difficulty in dealing with anger will be your unwillingness to believe that God's way of handling life's unfair circumstances is the best way."