Lots of people were Jews. Should Jews accept every single one of them as the Messiah?
http://whatjewsbelieve.org
http://www.aish.com/jw/s/48892792.html
http://www.jewfaq.org/moshiach.htm
http://jewsforjudaism.org/index.php?option=com_content&task=view&id=374&Itemid=234