If bacteria can live on a bar of soap why wash our hands to kill the germs using soap if it does not kill the germs?

While it is true that hand washing with plain soap doesn't actually kill all germs, hand washing is still a vital part of disease prevention. The mechanical action of hand washing--both the flushing action of the running water and the friction from the rubbing together of your hands--removes harmful pathogens. And that's why hand washing is considered so important to public health.

*Proper hand washing technique: use very warm water and soap, briskly wash and rub hands and between fingers with suds for a minimum of 20 to 30 seconds, rinse and dry on clean towel. To know if you are washing your hands long enough for the germs to be removed from your hands, sing two verses of Mary Had a Little Lamb or sing Happy Birthday twice before you stop washing and rubbing them with the soap suds.