That's a funny word, didn't know it was an -ism...
On a serious note, does anyone here actually know what it means that he was "raised Jewish"?
In today's day and age, anything can be an -ism
On the serious note, the way I understand it is when someone says he "raised Jewish" or for that matter להבדיל raised anything else, it means that he never saw being Jewish as part of his identity, but rather a religion practiced (to one extent or another) in his family.
Unlike many on this forum, for whom being Jewish is not a religious issue, but rather an identity issue, for many people who were like תינוקות שנשבו, Judaism is just another religion and belief system. However, as long as they have a Yiddishe neshomo, לא ידח ממנו נדח and there's hope that they will eventually connect with their true identity and with the aibershter.