Thanks for writing. You seem to be mixing up Tzippora and Ruth. Moses married Tzippora the Midianite (Exodus 2). It was Ruth, the Moabite, who said to Naomi, "your people are my people" (Book of Ruth 1). But I think I understand the point you are trying to make.
The Torah forbids intermarriage, and the Torah sets certain guidelines for what is required in order to convert to Judaism.
Such guidelines shouldn’t strike us as irrational or excessive: To become a US citizen, you need to go through a certain process, the end of which is to "pledge allegiance to the flag" and to agree to abide by all the laws of the US. If a person were to say, "I accept all the laws except the one requiring that I pay income tax," or, "except for the law that I not discriminate against minorities," he is likely to be rejected for citizenship — and rightly so — no matter how otherwise loyal he has been or will be. This should be true for most countries.
So it is when becoming a member of the Jewish People: One needs to go through the process of circumcision (for a male), ritual immersion, and acceptance of the Torah’s 613 commandments. This process must be supervised by knowledgeable rabbis. But if someone were to say, "I’ll accept all of Judaism, except for the law to abstain from eating milk and meat together," or "except for the law to observe Shabbat," then he cannot be accepted as a member of our people.
[This is not true for someone born Jewish. Like US citizenship, a born Jew doesn’t lose his Jewishness for breaking the law.]
Note that Ruth said "your people are my people" only after Naomi tried three times to send her back and discourage her. From Naomi’s example, the halacha is derived that we try somewhat to dissuade potential converts in order to test their sincerity.
Note, too, that Moses married Tzippora before the Torah was given at Mount Sinai. The rules for conversion had not as yet been set down and commanded. Then it was enough to swear off idol worship, accept belief in God and basic morality. At Mount Sinai, God gave us the Torah and its 613 laws. Among the 613 laws are those dealing with conversions.
