He was raised as a Catholic, but turned his back on it.
Scurrilous liars will fixate on his early Catholicism and try to pass him off as a Christian, but they always overlook his suppression and hatred of the church, he wanted to occupy the Vatican after Mussolini was toppled "getting out the whole lot of swine" (LB Darmstadt, 171, 26/07/43). After a conversation with Hitler about the future of Nazi occupied Russia Goebells said "there is, namely, an insoluble opposition between the Christian and a Germanic-heroic world view" (TBJG, II/2 499-500, 13/12/41).
Bormann (who never went against Hiitler's wishes) declared that National Socialism and Christianity were incompatible.
I could go on if you like the truth is Hitler was not a Christian in fact there were in reality more Pagans in the NAZI government than anything (Himmler certainly and Goebells arguably) they used Pagan symbols, Pagan rituals and Hitler himself was something of an occultist.
I'm not using these facts to promote an attack on Paganism, because for all the evils of the Third Reich they were most definitely NOT the fault of religion.