So you could take the time to understand those nice big words in the lie of the Khazarian myth but you didn't have time to try to understand the Christian religion? See this is why again you need to discard the preterist heresy.
Your dad's faith in the true religion and true understanding of Jesus is not something you can control. It is important you tell him the truth. If the blind lead the blind they both merely end up in the ditch. This is more of a reason you should renounce the heresy and convert to Christianity, then you can actually tell him the real Gospel with understanding that he also could believe and be saved while there is still time, or which he will disbelieve and have no more excuses, they can't feign ignorance in front of the omniscient God, only those with true and correct faith shall be saved, praise Jesus.
How would you offer hope to a dying man?
Give us an example of what you would say to him.