Jesus warned us he'd take away our lampstands if we're anything short of faithful. That even the lukewarm don't get a slide. This is in the very last book of scripture itself.
"Remember therefore from where you have fallen; repent, and do the works you did at first. If not, I will come to you and remove your lampstand from its place, unless you repent." - Rev 2:5
In his earthly ministry he also warned you: "The one who endures to the end will be saved." - Matthew 24:13
Hear the words of the Lord himself. Not the words of men.