According to a broad definition, a mystic is an individual who has a (usually intense) personal relationship with a Higher Power. Spiritual, intangible, invisible, supernatural power.
The raison d’être for this relationship is usually to serve this Higher Power. Which from time to time (usually) or continuously (rarely) supplies the mystic in question with knowledge and instructions that the latter needs to serve this Power in the most efficient way.
In addition, this spiritual entity (which is immensely powerful if not omnipotent) protects the life and health of its servant (i.e. from accidents, enemy fire or assassinations). And sometimes even performs miracles (i.e. the Reichstag Fire) that the mystic needs to do his job.
For a monotheist (Christian, Muslim, Jew or deist) this Higher Power is one Supreme Being – God. Yahweh, Allah, the Holy Trinity (which in Christianity is one entity, not three), Universal Creator, etc. For a polytheist (pagan) it is represented by a team of supernatural spiritual beings (with or without a leader, depending on a specific religion followed by the pagan in question).
An occultist, by definition, is the one who uses one or more “occult sciences” (“occult practices”) to achieve certain objectives (“good” or “bad”) via manipulation of supernatural forces.
By this definition, Adolf Hitler was definitely not an occultist and no less definitely a mystic (although whether he was a deist or a pagan, is uncertain). On the one hand, sometimes it appears that Adolf Hitler was a mystical, passionate deist.
Looks like he believed in One True Omnipotent God (but not in the Christian God although he was raised Catholic in a very Catholic environment). And in the Natural Law (in fact, the whole Nazi ideology was built on the concept of the Natural Law – as perceived by the Nazis, of course). And in somewhat mysterious Providence.
The latter for him was not the interference of God in this world – it was God. Like a proper deist, Adolf Hitler believed that God does not interfere in the affairs of this world directly but only through His ‘chosen people’. Both nations and individuals. And, of course, by helping both accomplish their Mission.
On the other hand, sometimes (i.e. judging from some passages in Mein Kampf), Adolf Hitler appears to de-facto worship two deities – Creator (God, Providence) and Nature. Or maybe even three as Providence/Fate sometimes appears to be quite different from Creator/God. Which makes him a polytheist (pagan).
Regardless of these religious uncertainty, Adolf Hitler did sincerely believe that the Germans are (and have been for millennia) God’s chosen people and he – Adolf Hitler – was God’s chosen individual. His missionary in this world (His Messiah, if you will).
There is some (largely uncorroborated) speculation that Adolf Hitler not only believed in reincarnation, but considered himself a reincarnation of no other than Holly Roman Emperor Frederick I Barbarossa.
In other words, there is some speculation that Adolf Hitler believed in the well-known legend about the abovementioned Kaiser. According to this legend, Frederick I Barbarossa did not die in 1190, but is asleep with his knights in a cave in the Kyffhäuser Mountain in Thuringia.
And when his beloved Germany finds itself in an existential danger, he will awake, reincarnate as a great leader, save Germany from this existential threat and restore it to its greatness, power and glory.
Consequently, Hitler deeply and sincerely believed that God will help him and Germany accomplish this Divine Mission by (1) revealing to him personally the best solution, decision and the course of action in every situation; and (2) by performing miracles that Hitler and Germany need to accomplish this Mission Impossible. Impossible without these miracles that is.
Hence, although in many cases Adolf Hitler behaved like a shrewd and pragmatic politician, a lot of his decisions (including those of absolutely critical and even vital importance) were based on these ‘revelations’ and expectations of miracles. Which on a number of occasions led to disastrous blunders and ultimately resulted in a total military defeat, the demise of the Third Reich and to the suicide of its Führer Adolf Hitler.
Another important (and very powerful) factor that contributed to Hitler’s downfall was his megalomania. Which, according to Merriam-Webster dictionary, is an obsessive (maniacal) desire for great or grandiose performance.
Megalomania is considered a delusional mental illness marked by feelings of personal omnipotence and grandeur. For Adolf Hitler, these feelings originated in his mysticism; more precisely, in his deep belief in his “messianic destiny”, his being the individual chosen by the Almighty God to fight and win the existential war and to make the Germans – “God’s chosen people”- the masters of our world (i.e. of the human civilization).
And were amplified with his bipolar disorder and his cardinal (and very much deadly) sins of pride and wrath. Which predictably led to colossal blunders and no less predictably catastrophic results. For himself, his nation, his country and his whole civilization – the Third Reich.