LORD, you always give me justice when I bring a case before you. Now let me bring you this complaint: Why are the wicked so prosperous? Why are evil people so happy? You have planted them, and they have taken root and prospered. Your name is on their lips, but in their hearts they give you no credit at all... Then the LORD replied to me, "If racing against mere men makes you tired, how will you race against horses? If you stumble and fall on open ground, what will you do in the thickets near the Jordan?"
These questions from Jeremiah are not different from questions that have been asked throughout history and are often heard today. Why do wicked people prosper? Why do good people suffer? How can a loving and benevolent god permit children to suffer from AIDS, hunger, abuse, etc? They are the same questions Job asked, that were asked in the Psalms.
God's reply here is a little bit different from the reply he gave to Job. To Job, he responded 'Who are you to be questioning me? Were you there when I created...' But to Jeremiah, he responds 'If you think this is bad, you ain't seen nothing yet.' I think I would rather have gotten the response that he gave Job.
While I do often find myself asking these kinds of questions, I try (not always successfully) to not demand answers so much as to adopt the attitude of the Psalmist - 'Still I will praise you, Lord.'