Besides the Jews, Hitler targeted anyone else he felt would do damage to the "gene pool" he hoped to create. His ethnic cleansing included the Romanians (gypsies), Catholics, homosexuals, political dissenters, etc.

One thing is sure: when dealing with mental illness, nothing makes sense because the mentally ill do not see things the way the rest of the world does: they have a different reality and their own set of rules. It is amazing and horrifying that one man was able to lead a nation to kill so many innocent people.

I think Amy has a very valid point here, and this is something that has been going on everywhere and I guess will continue to go on. Leaders, politicians, just about everyone who wants to gain a following but can't solve the problems that their followers may have, find this an easy way out. Find a scape goat. Preferably a relatively smaller group and one that is better off. Place the burden of all the misery on that group. And that's it.

The members whom you want to join your following feel you have redeemed them of their problems and provided a solution which they had never thought of. You have your following and they have something to do, even if it isn't something that is going to help them in any way.

Hitler used the Jews as a target for the anger of the disenfranchised masses of Germany.  He repeatedly told them that the Jews were the reason that Germany had economic problems and why there wasn't enough food.  He had cartoons drawn to portray them in ugly ways to reinforce his ideas...it was very 1984 like...all to get rid of a people whom he looked down upon for various reasons--some of which are listed above. 

I don't know that any of us have the exact reason Hitler did it.  While I recognize Hitler's military and leadership prowess (and even his genius), I lean toward the fact that this man was a crazy sociopath.

I think we make a mistake when we attribute the Holocaust to Hitler alone. As his been pointed out in earlier posts, anti-Semitism was ubiquitous in Europe. At an early age, Hitler was exposed to anti-Semitic literature. He was a great fan of the music of Richard Wagner who was an unrepentant anti-Semite. As a teenager, he often read a publication somewhat pornographic in nature known as Ostara, which was anti-Semitic in nature. Hitler was first and last a product of his time. No one man, no matter how charismatic, could have generated enough support for such a horrible project. Those who worked with him were as anti-Semitic as he, and were the product of anti-Semitic parents.

The main problem in Europe with the Jews is that they were first of all not Christian, and secondly insisted on preserving their own religious identity in dress, diet, and custom. They were always "outsiders," and scorned/despised accordingly.

For those interested, an excellent source to discuss Hitler's anti-Semitism and the Fuerherprinzep, read R.G.L. Waite's The Psychopathic God. 

Was not the Jews lack of nationality and their claim to a separate race that was part of the issue? As such, Jews were, in Hitler's eyes, a threat, as they could never become fully involved in the national spirit that he was working so hard to stoke up. The fact that Jews had a claim to a shared heritage and identity that superceded any claim to belonging to a country made them a threat.

Hitler shared the views of many of his contemporaries (read up on eugenics if you want to find some of those contemporaries, but count Woodrow Wilson as one of them) that certain races were superior to others.  Hitler believed that cleansing Germany of the undesireable races would help them to return to glory.

Finding a rational explanation for madness is perhaps an impossible task, but Hitler's perverted exercise of political power is more understandable in its perpetration of evil.

Making the Jews scapegoats served a political purpose; it provided a "reason" for all of Germany's woes and directed post-World War I public fear and frustration toward a single target. Exterminating Jews also enriched the Third Reich financially; businesses and private assets were confiscated. Land, homes, and possessions were appropriated by the Nazis. This greed was carried to the most obscene extreme when gold teeth and fillings were "harvested" from the Jewish dead. Even now, some German families are locating and recovering family treasures once stolen by the Nazis.

No single, simple explanation can explain Hitler's determination to eradicate the Jewish people. It was a perfect storm of madness, hatred, political power, and naked greed.

This depends on what level you are talking about this -- why he said he wanted to kill Jews or what his "real" reasons were.

What Hitler talked about was the idea that Jews were a kind of subhuman who could only destroy civilizations. He believed in a three-part categorization of human beings. Aryans, at the top, were the only ones able to create civilizations. They were called "culture-creating" people. The next category was "culture-bearing" people like Latins and some Asians -- they could maintain a culture once it was created but could not make their own. Finally, there were "culture-destroying" people like blacks and Jews. They would destroy cultures out of incompetence and malice and greed.

Hitler believed that Germany had become infested with too many Jews and that was why it was no longer able to hold its "rightful" dominant place in the world. This is why he wanted to get rid of Jews.

Here's a link to a part of Mein Kampf where he talks about this.

http://www.crusader.net/texts/mk/mkv1ch11.html

The relevant portion begins

If we were to divide mankind into three groups, the foundersof culture, the bearers of culture, the destroyers of culture, only the Aryan could be considered as the representative of the first group.

Now... as far as why he would believe such a thing... that's beyond me. I don't do psychological analysis of historical figures, though many people are happy to try.