Lord Voldemort manifests a hatred for witches and wizards who are of mixed-blood origin, thus his support for the ideology of Salazar Slytherin and his contribution to the utilization of the Chamber of Secrets to achieve Slytherin’s intention to eliminate all mixed-blood witches and wizards at Hogwarts. However, Riddle himself is not pure-blooded: his father is a muggle and his mother, a witch.

Hitler-like?

The former German Chancellor, Adolph Hitler (a Christian who once aspired to become an abbot) was raised in a religious culture marked by anti-semitism. There is a possibility that he feared he may have jewish blood himself. This fear stems from a rumor that Hitler’s grandmother, Anna Maria Schicklgruber was working as a servant in a Jewish Household, while pregnant. Schicklgruber never named the father of her illegitimate child, Alois, who would later become the abusive father of Adolph. While there is no reliable evidence that points to Hitler’s true grandfather, the most popular rumor is that his grandparent had in fact, been a Jew. The following statement, taken from the the Council of Basel, is one of the church documents that contributed to Hitler's anti-semitic mindset:

“[The church] firmly believes, professes and preaches that all those who are outside the catholic church not only pagans but also Jews or heretics and schismatics, cannot share in eternal life and will gointo the everlasting fire which was prepared for the devil and his angels, unless they are joined to the catholic church before the end of their lives…”

Under Hitler Germany, the Christians were all Germans. On the other hand, Jews were led to extermination, in what would be regarded as one of the darkest chapters in human history. Hitler was also a staunch admirer of an anti-Semite by the name of Robert Wagner. Wagner once quoted that one “cannot declare allegiance to Jesus and to those who nailed him on the cross.” Moreover, the fourth of the Nazi party’s 25 Points, states the following:

Only those who are our fellow countrymen can become citizens. Only those who have German blood, regardless of creed, can be our countrymen. Hence no Jew can be a countryman.”

Is Voldemort the magical world’s equivalent to Hitler? His hatred for mixed bloods is a paradox in the context of his own lineage. Voldemort had much rage towards his father, Riddle Sr., for having abandoned his mother, whose death at birth would land him in an orphanage which he detests as well---an attitude we discover (via his diary) in his conversation with former Hogwarts Headmaster Dippet, in which he expresses repugnance for his home. Riddle eventually killed his own father and grandparents. Hitler’s family life was dysfunctional as well, having been abused by his father Alois, who once attacked the young Adolph until he thought and feared that he had murdered his son.

Motives for Extermination

If this is one of Voldemort's motives, then a witch or wizard’s predisposition for the dark side, or otherwise, would not matter, if he or she were of mixed blood origin. However, not all pure-bloods are on the dark side, and there have been pure-blooded individuals who were made to suffer at the hands of Voldemort’s Death Eaters, such as Frank and Alice Longbottom, parents of Neville and members of the first Order of the Phoenix, who were tortured into insanity by Bellatrix Lestrange. Sirius Black is another outstanding example of a pure-blood who is opposed to the dark side, in spite of his familial affiliation with a Death Eater’s wife, Narcissa Black Malfoy, not to mention his notorious pure-blooded family. Just take a look at the portrait of Sirius’ mother and the taunts she directs at those she deems of worthless lineage.

Additionally, we do not know all information as regards the bloodlines of Voldemort’s supporters. We cannot conclude that all Slytherins are pure-blooded, even if that was his house and there may be some innate bias on his part. We simply have to look at Riddle’s own history to know that there are mixed-blood Slytherins, which may point out at the Sorting Hat’s judgement as questionable. The Hogwarts founders had placed their thinking into the hat, and Slytherin stood out as the only founder who wanted pure-bloods, then why was Tom Jr. placed in Slytherin? We may conclude that, that was the best house for Riddle, along with the possibility that no student accepted into Hogwarts had ever been asked to leave if no house is suitable for him or her, because as readers, there have been no indication in the books that a witch or wizard was not sorted into a house, because he or she did not fit any. It is best to conclude that a student is placed in the house that suited him or her.

This is where the Chamber of Secrets comes in, which Slytherin built for the elimination of all mixed-bloods, thus no mix-blooded student, regardless of their house, was immune. So, how did mix-blooded Tom control the basilisk, without dying? Was he simply an extraordinarily brilliant student who was able to find a means of controlling the creature, the same way as Harry Potter was able to win the respect of a potentially dangerous hippogriff? Possibly. Was the belief that the basilisk---as a specialty killer of mixed-bloods---inaccurate? If that was so, then why would Slytherin build the chamber if it would not serve the purpose he intended?

Whether or not, it was the error of the Sorting Hat (aging?), or the brilliance of Tom Riddle, Lord Voldemort’s hatred is generally directed towards those who are obviously not on his side, and being a mixed-blood would only heighten that hate.