Titus 1:15

All things are pure to the pure; but to the contaminated and the faithless nothing is pure, nay, their very minds and consciences are tainted.

Romans 14:20

Do not, for the sake of food, be tearing down God's work. All food indeed is ceremonially clean, but a man is in the wrong if his food proves a stumbling-block.

Romans 14:23

But he who has misgivings, and yet eats meat, is condemned already, because his action is not based on faith; and whatever is not based on faith is sin.

Romans 14:14

I know and am persuaded in the Lord Jesus that nothing is in itself unclean; but any food is "unclean" for one who considers it "unclean."

Matthew 15:18

while what comes out of the mouth comes from the heart??nd that is what defiles a man.

Acts 10:15

And again a second time came to him a voice, saying, "What God has cleansed you must not call common."

Luke 11:39-41

but the Lord said to him. "You Pharisee do cleanse the outside of your cup or plate, but your secret heart is full of extortion and wickedness.

1 Corinthians 6:12-13

"All things are lawful for me"? Yes, but not all things are good for me. "All things are lawful for me"? Yes, but I will not let myself be enslaved by the power of any.

1 Corinthians 8:7

But that "knowledge" is not possessed by all; but some, accustomed until now to the idol, eat food as that which has actually been offered to an idol, and so their conscience, being still weak, is defiled.

1 Corinthians 10:23

"All things are lawful," you say? But not all things are expedient; "all things are lawful"; but not all build up.

1 Corinthians 10:25

Eat anything that is for sale in the markets, asking no questions for conscience sake;

1 Corinthians 10:31

Because whether you are eating or whether you are drinking, you are to do it all for the glory of God.

1 Corinthians 11:27-29

So he that eats the bread or drinks the cup of the Lord unworthy must answer for a sin against the body and blood of the Lord.

1 Timothy 4:3-4

who discourage marriage, and enjoin abstinence from foods which God created to be received with thankfulness, by those who believe, and have a clear knowledge of the truth.

1 Timothy 6:5

and wrangling between men whose minds are corrupt and destitute of the truth; who suppose that godliness is a source of gain.

Hebrews 9:14

how much more shall the blood of Christ, who through his eternal spirit offered himself free from blemish to God, cleanse your conscience from dead works unto the service of an ever-living God!

Hebrews 10:22

let us draw near with a true heart, in full assurance of faith, our hearts sprinkled from and evil conscience, and our bodies bathed in pure water.

Treasury of Scripture Knowledge

Summary

Unto the pure all things are pure: but unto them that are defiled and unbelieving is nothing pure; but even their mind and conscience is defiled.

General references

Bible References

The pure

Luke 11:39
but the Lord said to him. "You Pharisee do cleanse the outside of your cup or plate, but your secret heart is full of extortion and wickedness.
Acts 10:15
And again a second time came to him a voice, saying, "What God has cleansed you must not call common."
Romans 14:14
I know and am persuaded in the Lord Jesus that nothing is in itself unclean; but any food is "unclean" for one who considers it "unclean."
1 Corinthians 6:12
"All things are lawful for me"? Yes, but not all things are good for me. "All things are lawful for me"? Yes, but I will not let myself be enslaved by the power of any.
1 Corinthians 10:23
"All things are lawful," you say? But not all things are expedient; "all things are lawful"; but not all build up.
1 Timothy 4:3
who discourage marriage, and enjoin abstinence from foods which God created to be received with thankfulness, by those who believe, and have a clear knowledge of the truth.

Their

1 Corinthians 8:7
But that "knowledge" is not possessed by all; but some, accustomed until now to the idol, eat food as that which has actually been offered to an idol, and so their conscience, being still weak, is defiled.
Hebrews 9:14
how much more shall the blood of Christ, who through his eternal spirit offered himself free from blemish to God, cleanse your conscience from dead works unto the service of an ever-living God!
Hebrews 10:22
let us draw near with a true heart, in full assurance of faith, our hearts sprinkled from and evil conscience, and our bodies bathed in pure water.

General references

Acts 24:16
"Hence I too endeavor to have a conscience void of offense toward God and men alway.