1 Corinthians 8:4

As to eating things which have been sacrificed to idols, we are fully aware that an idol is nothing in the world, and that there is no God but One.

1 Corinthians 10:19-20

Do I mean that a thing sacrificed to an idol is what it claims to be, or that an idol is a real thing?

1 Timothy 4:1

Now the Spirit expressly declares that in later times some will fall away from the faith, giving heed to deceiving spirits and the teachings of demons;

Revelation 9:20

But the rest of mankind who were not killed by these plagues, did not even then repent and leave the things they had made, so as to cease worshipping the demons, and the idols of gold and silver, bronze, stone, and wood, which can neither see nor hear, nor move.

Treasury of Scripture Knowledge

Summary

They sacrificed unto devils, not to God; to gods whom they knew not, to new gods that came newly up, whom your fathers feared not.

Bible References

Sacrificed

1 Corinthians 10:20
No, but that which the Gentiles sacrifice, they sacrifice to demons, not to God; and I would not have you have fellowship with one another through the demons.
1 Timothy 4:1
Now the Spirit expressly declares that in later times some will fall away from the faith, giving heed to deceiving spirits and the teachings of demons;
Revelation 9:20
But the rest of mankind who were not killed by these plagues, did not even then repent and leave the things they had made, so as to cease worshipping the demons, and the idols of gold and silver, bronze, stone, and wood, which can neither see nor hear, nor move.

Not to god

1 Corinthians 8:4
As to eating things which have been sacrificed to idols, we are fully aware that an idol is nothing in the world, and that there is no God but One.
1 Corinthians 10:19
Do I mean that a thing sacrificed to an idol is what it claims to be, or that an idol is a real thing?