Hi. What an interesting thread. This isn't a theoretical exercise for me, because someone we knew and loved went the way of Heb. 6:4-6 & II Peter 2: 19-22.
Here are some thoughts I've had on the topic.
First, to take guard ourselves. II Peter 1 explains what to add to our faith: virtue, knowledge, self control, perseverance, godliness, brotherly kindness, and love. With these we're guarded from barrenness and unfruitfulness.
The man we know who fell had no conscience.
Hebrews has so much on taking heed.
I think this is something we can all agree on, to take heed to ourselves and to grow in godliness. What happens to the deliberately wicked is up to God.