'Contaminated' in the Bible

but that we write to them that they abstain from things contaminated by idols and from fornication and from what is strangled and from blood.

But not everyone has this knowledge. Some people are so accustomed to idolatry that when they eat food that has been offered to an idol, their conscience becomes contaminated because it is weak.

See to it that no one falls short of God’s grace; that no root of resentment springs up and causes trouble, and by it many be defiled;