Is the Hadith "Two men are punished before idol worshippers: a man who did not act upon his knowledge, and a man who worshipped Allah out of ignorance" authentic?

We do not know of a Hadith with this exact wording. The Sunnah indicates that the first three people with whom the Fire will be kindled are: the ostentatious fighter, the ostentatious scholar, and the ostentatious giver of charity. The ignorant worshipper is not among them. There is a weak Hadith stating that the Zabaniyah (angels of punishment) will hasten to the immoral reciters of the Quran more quickly than to the idol worshippers, and it will be said to them: "He who knows is not like him who does not know."