Greek word here for wrestle is pale: meaning partake in warfare between the saints and the powers who are against God.
There are actually four kinds of "Spirit Rebels" or demons mentioned here:
1. Principalities, greek word is archas. In Satan's kingdom, these are the high rulers. Those who carry the most in "rank" in a military standing.
Thanks to Christ and the completion on the cross, we know these (as well as Satan) are defeated for those who believe in Christ. See Eph 1:21 and Col 2:10.
2. Next we see the Greek word of exousias meaning authorities. These are those demons who get their empowerment and orders from their "chief ruler", Satan. Most of the modern version Bibles just read "Powers"
3. Third is "rulers of the darkness of this age" Greek word, kosmokratopas. This type is seen many times in our Bible... Dan 10:13-21 Eph 1:21 and Col 1:16-18. There are many in this world right this minute. These are the Rulers of anything today who do not follow Christ and his teachings. These are the rulers with no morals, with little to do with religion or even attempting to do the right thing. These people are the worshipers of money, power and fame.
4. The final kind is spiritual wickedness. Greek word, pneumatika ponerias, we see they are in the heavenlies and are of Satan.
Heavenlies: http://biblesuite.com/greek/2032.htm
2032 epouránios (an adjective, derived from 1909 /epí, "on, fitting," which intensifies 3772 /ouranós, "heaven") – properly, heavenly, referring to the impact of heaven's influence on the particular situation or person.
[The prefix (epi) shows this always "fits" – from the standpoint of heaven.]
This was the best definition I could find on heavenlies, I think it is a pretty good one.
So, does that mean there are devils and demons in Heaven? No, not in the high heavens where God is. The best reading I came across was this commentary by Jon Gill:
"but in the aerial heavens, where the power or posse of devils reside,
and where they are above us, over our heads, overlooking us, and
watching every advantage against us;"
http://www.biblestudytools.com/commentaries/gills-exposition-of-the-bible/ephesians-6-12.html
There is the web site if you wish to read it all, good stuff!
So, are there demons, devils and evil spirits? The Bible says yes. Most Biblical scholars say yes.
What can be done about it? Well read on in Eph and find we are to "Stand our ground" and there is a Full Armor of God that we can put on to protect us!
Eph 6:13-18 :
13 Therefore put on the full armor of God, so that when the day of evil comes, you may be able to stand your ground, and after you have done everything, to stand. 14 Stand firm then, with the belt of truth buckled around your waist, with the breastplate of righteousness in place, 15 and with your feet fitted with the readiness that comes from the gospel of peace. 16 In addition to all this, take up the shield of faith, with which you can extinguish all the flaming arrows of the evil one. 17 Take the helmet of salvation and the sword of the Spirit, which is the word of God. 18 And pray in the Spirit on all occasions with all kinds of prayers and requests. With this in mind, be alert and always keep on praying for all the saints.
13 Therefore put on the full armor of God, so that when the day of evil comes, you may be able to stand your ground, and after you have done everything, to stand. 14 Stand firm then, with the belt of truth buckled around your waist, with the breastplate of righteousness in place, 15 and with your feet fitted with the readiness that comes from the gospel of peace. 16 In addition to all this, take up the shield of faith, with which you can extinguish all the flaming arrows of the evil one. 17 Take the helmet of salvation and the sword of the Spirit, which is the word of God. 18 And pray in the Spirit on all occasions with all kinds of prayers and requests. With this in mind, be alert and always keep on praying for all the saints.
Blessings on all!!
Calabash