Canaris,
most studies on the topic (re: abstinence-only programs) do not support your assertion. Comprehensive sex education has been shown to be effective, not only in decreasing pregnancy and disease transmission rates but also in delaying the initiation of sexual activity. Abstinence-only programs have not been shown to be effective.
In regards to psychologists... According to Wikipedia, abstinence-only education has been criticized in official statements by the American Psychological Association, the American Medical Association, the National Association of School Psychologists, the Society for Adolescent Medicine, the American College Health Association, the American Academy of Pediatrics, and the American Public Health Association, which all maintain that sex education needs to be comprehensive to be effective.
Besides, if being educated and prepared for safer sex practices was actually harmful, by the same token educating people on how to use a gun safely would increase the rates of violent crime and gun-related accidents (of course the opposite is true).