Hell fire threats are the wrong way to spread the gospel. The Good News is that there is a solution/remedy for this lost and blind condition we are all born with that is caused by the wages of sin that results in death. That is Jesus. God's grace offers salvation from what? From spiritual death which is separation from God and His final judgment, destruction - regardless of whether it's eternal or not. I am one to think that the unbelievers are thrown into the Lake of Fire and destroyed, like a piece of paper is burned - it doesn't keep burning forever. That would be an indestructible destruction - doesn't make sense.
You must be gentle and loving when witnessing or evangelizing, but you can't leave out what the person is being saved from. What they will lose is much greater, a free gift of eternal life. I do not think any Christian relishes a judgment of eternal torture, both can many argue rationally that it is just. I just think it was passed down as a traditional concept. The Greek word, aionios when applied to this temporal realm (that will pass away), means ages, generations, lifetimes, epochs. When applied to God, His domain or our salvation it means eternal. Death and Hades will be thrown into the Lake of Fire and be destroyed. Destroy means to put an end to, out if existence.