Why does Eliezer believe that man is stronger than God? Why does he call himself the “former mystic”?

Eliezer angrily compares God's greatness with the weakness of the assembled Jews. Thousands of men prostrate themselves to God, but Eliezer refuses to bless a God who has allowed crematories to exist. Though he used to be a mystic and used to love New Year's Day, this year he accuses God of injustice and feels strong, yet alone, without God or man.