Obviously, we aren't going to survive if we intermarry with everyone else and raise our kids as just a muddle of everything. Our only route to survival is for Jewish people to marry Jewish people and bring their kids up as good Jews.

Chabad dot org

https://www.chabad.org/library/article_cdo/aid/39606/jewish/Why-Do-Jews-Exclude-Other-People.htm

https://web.archive.org/web/20071110150658/https://www.chabad.org/library/article_cdo/aid/39606/jewish/Why-Do-Jews-Exclude-Other-People.htm