Jewish dating more perhaps than amongst some other religious groups believe it is very important to date and ultimately marry someone from the Jewish community.  Jewish dating is designed to allow both parties to review their goals, background and understanding of such issues as their religious beliefs.  The best chance of a successful marriage is when both parties have similar expectations about marriage and life in general.

When the Jewish dating is done through traditional customs and practices, the decisions are being made by both parties as to the suitability of the marriage. When there is a mixture of religions or cultures, it is very difficult to even begin to address and settle questions or concerns, because they may not be understood as a concern by the opposite party.  When a person is raised conservatively, there is often no realization that there way be an alternative way of looking at the subject.  It is often just assumed that something is so.  This doesn't even have to be major topics, it can be something as minute as a personal mannerism.  It is also not necessarily tied to the religious beliefs of either party. 

The point is that it would be rare that all potential issues which could arise due to a person who is Jewish, dating a non Jewish person. For example, if you are choosing to mix religions, who gets to make the decision about which religion the children will be raised in.  It's all very well to say that you'll teach both religions, or both religions and then let them choose when they are old enough.  In practice that may only lead to a child who is confused.  Another issue which may not be considered is where the couple will be married and who will perform the ceremony if it is to be a religious ceremony. 

While there is a movement among many religions, including Judaism to be more lenient and accepting of one another's beliefs, it is still a difficult issue to just give up the tenets and beliefs you have been raised with, no matter whether you personally accept everything you've been taught or not.

Jewish dating within the boundaries of Judaism can even encompass many different types of Jews, and many different belief systems which are still considered Judaism.The tension between orthodox Jews and conservative Jews can create sparks and recommendations by the parents or older generations that the people who espouse the two different Jewish belief systems should not date or marry.

So, it is critically important that even amongst Jewish couples that the issue of how serious they are about the beliefs, traditions and customs of Jewry.  If there is too much of a gap between the two people, it is better to find out about it prior to the marriage than after.

It is all part of the pattern of getting to know each other through calm and rational communication which makes it possible to determine the other person's beliefs, not only on the subject of religion, but other important aspects of life as well.