Just not true. Jude uses this word and is absolutely speaking of unbelievers—those not having the Spirit.
Translated "sensual persons" in the NKJV.
Jude 19 These are sensual persons, who cause divisions, not having the Spirit.
The NIV translates using 4 words, "follow mere natural instincts."
Jude 19 These are the people who divide you, who follow mere natural instincts and do not have the Spirit.
NASB translates it "worldly-minded."
Jude 19 These are the ones who cause divisions, worldly-minded, devoid of the Spirit.
If you're going to argue these are believers, then you must take the absurd position that believers not only consider the things of God foolish, but are also themselves "devoid of the Spirit."
No I don't. Just because something is used elsewhere doesn't negate my point, which is based on the context in this passage. Bread is not always used as bread in which you eat. I could go on.