To wander from God's way of understanding is a very dangerous thing to do. Here in today's proverb we see just how dangerous this can be. According to Solomon the eventual end of the man who does this is a final resting place among those doubly dead.
The word "wander" is key to understanding this passage. This is the Hebrew word "taah" which means not just to wander off - but to err and go astray. The primary meaning is to err and to make a mistake. This word is used most often of thos who err or who are being misled in a moral or religious sense. It is the word used in Isaiah 53:6 when the prophet tells us, "All of us like sheep have gone astray, Each of us has turned to his own way; But the LORD has caused the iniquity of us all To fall on Him." To wander is to go astray of God's moral path - and to incur iniquity in His eyes. Therefore to wander is to go astray of God's path and God's will for us. The wandering here is to err from the "way of understanding." This phrase speaks of someone who no longer has discernment or any kind of spiritual insight. And since the phrase begins with the word "way" - it refers to someone whose very way of life turns from any spiritual insight and discernement and chooses instead a way of life guided by self and selfish desires and longings.
The picture we get now is not just someone wandering away from a single situation where advice is offered, but rather a situation where as a way of life he is turning from God's will and Word. This is basically the condition of a lost person. They reject the wisdom of God - the Word of God - and the way of God. They instead choose the world, their flesh, and the lies of the devil - since that is what we have learned the Holy Spirit has been sent into the world to convict us of in life.
What is important is the warning that is given to us in the second half of this proverb. The one who lives this way - "will rest in the assembly of the dead." For those who think this is a reference to spiritual death - or a lack of spiritual life and blessing here and now - the actual word for death here is, "departed spirits." This is a warning to turn from rebellion and purposeful rejection of God's will and way. The end of such a lifestyle is a life spent with those who are "doubly dead." They have died in this life losing their physical life - but infinitely worse they are devoid of spiritual life when they die physically - so - the place of their eternal dwelling is hell. That is why it is so important to reject the heart and mind that reject God's Word and way. To continue in it is to continue toward an abyss where there is no return. Far better to embrace God's way and Word now - to embrace repentance from our own fleshly mindset - to embrace a turn from ourselves to God - from our way to His. That will keep us from a rest that will be anything but rest. It will rescue us from a fate worse than death itself.