Yea, well, God says not to eat pork, and to kill old woman who dabble with supernatural forces, and that marrying my niece isn't incest, and that it's a good idea to deliver the virgin 10 year old daughters of neighbors you've invaded and slaughtered into slavery. It's possible that a rational person might not consider this an irresistable argument.
The kosher laws were given only to Israel for the express purpose of separating her from other countries. And it has worked well. Jews have maintained their identity despite having been exiled and scattered for almost 2000 years.