Spiritual concerns aside, there's a very simple ethical reason why humans should not be cloned, at least for now. Cloning is an infant technology. Dolly the sheep was cloned a mere 5 years ago. Dolly, 5 years old, shows signs of premature aging and severe arthritis, which may well owe to genetic defects. Other animal clones have exhibited problems as well.
Now, the modern-day Dr. Mengele's of the world are in a rush to experiment with human cloning. Either they're too stupid to realize the ethical dimension of what they're doing, or too sick to care, but the result of their experiment is a human being who may live a short, miserable life with incurable illnesses.
Until we've gotten to the point where we have thorough understanding of animal cloning, we shouldn't even think of cloning humans.