1 Corinthians 8:4

Therefore concerning the eating of food sacrificed to idols, we know that an idol is nothing in the world, and that there is no God but one.

1 Corinthians 10:19-20

What do I mean then? That a thing offered to idols is anything, or that an idol is anything?

1 Timothy 4:1

Now the Spirit expressly says that in later times some will fall away from the faith by giving heed to deceitful spirits and doctrines of demons,

Revelation 9:20

The rest of mankind, who were not killed by these plagues, did not repent of the works of their hands nor give up worshipping demons and idols of gold and silver and bronze and stone and wood, which can neither see nor hear nor walk;

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 I say that the things pagans sacrifice they offer to demons and not to God. I do not want you to be partners with demons.
1 Timothy 4:1
Now the Spirit expressly says that in later times some will fall away from the faith by giving heed to deceitful spirits and doctrines of demons,
Revelation 9:20
The rest of mankind, who were not killed by these plagues, did not repent of the works of their hands nor give up worshipping demons and idols of gold and silver and bronze and stone and wood, which can neither see nor hear nor walk;

Not to god

1 Corinthians 8:4
Therefore concerning the eating of food sacrificed to idols, we know that an idol is nothing in the world, and that there is no God but one.
1 Corinthians 10:19
What do I mean then? That a thing offered to idols is anything, or that an idol is anything?