>>25166
Turkbernd summed it up, but here's my take:
Khazars were a tribe of Turkic steppe people who gained influence over others and founded a state of considerable power on the Pontic steppes. At one point the ruling dynasty and the aristocracy converted to Judaism, about that time quite a few Jews moved there, fleeing from Byzantines.
The conversion might happened so the khagans could stop the foreign influence spreading in their court which originated from both Christian and Muslim sources. It might have been also a show of status: "the emperor might have Christianity and the caliph Islam, but I, the khagan, am the same, I have my own religion too".
One khagan wrote a letter to a rabbi in Hispania, it is one important source about this matter. Maybe it is available somewhere on the nets.
The general population - which consisted several folks, among them Hungarians for a while (tho the exact nature of the relations between the Magyar tribes and the Khazar Khaganate is unsure at best) - followed many religions and religious practices, among them only the Jews were Jews.
There are great many speculations about the topic, but the actual available information - just as for great many steppe people - is little.

>>25187
Well, the end of your post could read a little harsh.