They are looking to trap you with eloquent words. Continue to turn the tables back on them and don't answer when you don't want to. Tell them you need to do more research to settle your own questions which are no ones business but yours, "since you do not wsih to be accused of spreading" doubts.
As to Korah- ask them if he will get a resurrection - likely they will say no. The read them the scripture "So down they went, and all who belonged to them, alive into She′ol..." Guess they will get a resurrection per WT understanding of Sheol.