The Jehovah's Witnesses constantly say to love the person but to hate their sin. This "logic" obviously enables bigotry and promotes the disdain of others, especially in a cult context where "sin" means anything they tell you not to do (smoking, voting, celebrating a birthday, masturbation, thoughtcrime like sex appeal, whatever). The result is the toxic environment of a high control cult, its peer pressure and its rumors chatting about everyone, etc.
Here it's similar but a threat or wish of eternal torment is expressed. Not all Christians believe in hell (the scriptural basis for the doctrine is weak and subject to interpretation) and those who do often also believe in other temporary punishments of sorts like purgatory or karma, because they find untenable the idea of a supposedly loving creator who actively tricks its creation so that its destiny is eternal suffering. Then there's the fact that it's an imaginary being in a book of human tradition, there are good reasons to be moderate and agnostic. And if you're Christian, Jesus told you to love and to not judge, meaning that your hell threat is not only disrespectful and hateful but also illicit.
So it's easily reflected back, with an actual scriptural basis: Matthew 7:1-5 (do not judge and you shall be judged the same), so what could happen: Matthew 7:22-23 ("but Jeez, I preached in your name... plzzzzz!" "I never knew you; depart from me, you workers of lawlessness.")
So yeah, you should think before threatening people, hypocrite. When you speak for your group, you're also tainting its reputation. If your churches are empty, it's not for no reason. If yours somehow had actual divine support, there would be no unbeleivers. And as shown above, that's unlikely.
