A connection between idols (false gods) and demons (evil spirits) is seen in Deuteronomy 32:16-17,
“They stirred him to jealousy with strange gods; with abominations, they provoked him to anger. They sacrificed to demons that were no gods, to gods they had never known, to new gods that had come recently, whom your fathers never dreaded.’
I read somewhere in Hebrew text there is something called Synonymous parallelism which involves the deposition in the second part of what has already been expressed in the first, while simply sharing the words. I think it is done here in the verse above demons and strange gods are the same. It connects pagan worship with evil spirits. The false gods are in contrast with the true God, the Rock in Deuteronomy 15;17.
There is another important connection in Leviticus 17:7,
“They shall no more offer their sacrifices to demons, After whom they have played the harlot.”
Here these demons are other gods were worshipped by surrounding cultures. Demons were equaled with pagan gods in this passage.
It is no coincidence that demonic activity is associated with religions that embrace a multitude of gods and goddesses. A desire to have contact with the “spirit world” often focuses people on supernatural power apart from the power God offerss through a relationship with Jesus and Holy Spirit.
Satan desires to be worshipped (Matthew 4:9), and demons teach false doctrine to deceive (1 Timothy 4;1). Those who worship false gods are, wittingly or unwittingly, pledging their attendance to evil spirits who desire to usurp God’s rightful place in our hearts.
Whatever we serve more than God is an idol. and an idol should be nothing. It would not have power over us. This is where satan and his demons have true power over us. The love of money, the love of alcohol, drugs, sex, the list goes on and on. (1 Corinthians 8:4; Mark 5:7-8).
From Pity to Praise 