#1 First, he is misusing the meaning of the words. The concept is not that humanity is cranked out with machine-like precision, equal in every detail, but that all people are created with equal rights before the law. Thomas Jefferson never said that no person was smarter, swifter, stronger, or prettier than another person. In one specific document, he noted that the equality before the law is (or should be) inherent in every person from birth.
Jefferson was not claiming that there were no differences between individuals, but that there were no valid differences by birth such as were granted in Europe to royalty and nobility.
To turn that into a declaration of the equality of features among individuals is to betray a complete ignorance of the statement and how and why it was made.
(Implied in your correspondent’s ignorance is the fact that he would then try to extrapolate his misunderstanding of the equality of rights before the law into a claim that different populations of humanity might be better or less well-equipped to succeed in the world. That issue is not even addressed in the Declaration of Independence.)
#2 An absurd display of a genuine ignorance of history.
The Egyptians were a multi-ethnic civilization from the beginning and flourished for over 2,000 years. The Byzantine Empire was multi-ethnic and survived for 800 years (thriving for at least 400 of them). China, despite ignorant Western views that Chinese are “all the same” is a multi-ethnic society that has survived and thrived (with rising or falling periods, of course) for over 2,000 years.
The usual victim of this “racial purity” nonsense is Imperial Rome. However, Rome did not fall because it was simply multi-ethnic, it fell under the pressures of repeated violent invasions (and the Roman tradition carried on quite nicely in the multi-ethnic Eastern Empire where the violent invasions were more successfully held off).
#3 ::: sigh ::: The word Jew originated in English when the consonantal “D” dropped out of the word (probably influenced by the French Juif, but the group of people who are known by the word Jude in German are the same people who were called Joudaios in Greek. The Greek and German variants of the word are actually pronounced very closely. This argument is simply stupid. It is ignornace preying on ignorance.
As to the “racial purity” nonsense–only the “Aryan” supremecists even care about such an idiotic notion. Jews look upon themselves as the people who follow the laws of Moses, including converts and people who “marry into” the faith. It would be interesting to find one of these haters who can point to a Jewish claim of racial purity.
Judaeo-Christian is a bit more problematic (and many Jews will argue against a “Judaeo-Christian” tradition, considering how bad a heresy Christianity is to the Jewish faith and how horribly we heretics have treated the original believers). However, both groups accept as God’s Word the writings found in what Jews call the Tanakh and and Christians call the Old Testament. Both groups see that God as a loving God who created the world and calls humanity to act justly. Certainly, while Jews might wish to distance themselves from the people who followed Jesus, no Christian cam legitimately separate from the tradition (however re-interpreted) that originated with the Jews.
The “Jewish Race” is the older use of the word “race” that preceded the eighteenth century notions of categorizing people. It originally meant those people who “descended” either actually or in legend from a common acestor. Thus, the Romans were the “race” of Romulus; the Irish were the “Milesian race” descended from Milesius; the “Jewish race” descended from Abraham. (Note, that while looking to Romulus as their ancestor, the Romans were quite aware that other tribes had been brought into their group; every Jewish scholar realized that Abram/Abraham started with an already coherent tribe that included his cousins and servants.)
It was only after the early ethnologists “borrowed” the word race to describe the groups into which they would divide the world that we got caught up in the confusion of some ethnically “pure” Jewish race–that was not the meaning of the word when it was first used and is a mistaken application of the word, now.