Titus 1:15

To the pure all things are pure, but to those who are defiled and unbelieving nothing is pure. Both their mind and their conscience are defiled.

Romans 14:20

Do not tear down the work of God for the sake of food. All things indeed are pure; but it is evil for that man who eats with offense.

Romans 14:23

He that doubts is damned if he eats, because he eats not by faith. Whatever is not by faith is sin!

Romans 14:14

I know, and am persuaded by the Lord Jesus, that there is nothing unclean in itself. If someone thinks something is unclean it is unclean to him.

Matthew 15:18

That which comes out of the mouth, comes from the heart and makes a man unclean.

Acts 10:15

The voice spoke to him again the second time: You stop calling defiled that which God has cleansed.

Proverbs 21:4

Haughty eyes and a proud heart, and the arrogance and pride produced by the wicked are sin.

Haggai 2:13

Then Haggai asked: This person is defiled because he has touched a dead body. If he then touches any of these foods, will that make them defiled too? The priests answered, Yes.

Zechariah 7:5-6

Speak to all the people of the land and to the priests, saying: 'For the past seventy years did you fast for me when you fasted and mourned in the fifth and seventh months?

Luke 11:39-41

The Lord said: You Pharisees cleanse the outside of the cup and of the platter. Yet your inward part is full of extortion and wickedness.

1 Corinthians 6:12-13

All things are lawful to me, but all things are not expedient (profitable) (good). All things are lawful for me, but I will not be brought under the authority (power) (control) of anything.

1 Corinthians 8:7

Not all people know this. Some eat food offered to idols and their conscience being weak is defiled.

1 Corinthians 10:23

All things are lawful for me, but all things are not expedient (profitable). All things are lawful for me, but all things do not build up (confirm) (strengthen).

1 Corinthians 10:25

Eat whatever is sold in the meat market without asking questions for the sake of conscience.

1 Corinthians 10:31

Whether you eat, or drink, or whatever you do, do everything to the glory of God.

1 Corinthians 11:27-29

Whoever shall eat this bread, and drink this cup of the Lord, unworthily, shall be guilty of [sinning against] (falsely representing) the body and blood of the Lord.

1 Timothy 4:3-4

They will forbid marrying, [and command] to abstain from food, which God created to be received with thanksgiving by those who believe and know the truth.

1 Timothy 6:5

frictions between men corrupted in mind and lacking in truth, supposing that godliness is a way of gain.

Hebrews 9:14

The blood of Christ did even more. Through the eternal Spirit he offered himself without blemish to God and cleansed your conscience from dead works. Now we can serve (worship) the living God.

Hebrews 10:22

let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with 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.

Bible References

The pure

Luke 11:39
The Lord said: You Pharisees cleanse the outside of the cup and of the platter. Yet your inward part is full of extortion and wickedness.
Acts 10:15
The voice spoke to him again the second time: You stop calling defiled that which God has cleansed.
Romans 14:14
I know, and am persuaded by the Lord Jesus, that there is nothing unclean in itself. If someone thinks something is unclean it is unclean to him.
1 Corinthians 6:12
All things are lawful to me, but all things are not expedient (profitable) (good). All things are lawful for me, but I will not be brought under the authority (power) (control) of anything.
1 Corinthians 10:23
All things are lawful for me, but all things are not expedient (profitable). All things are lawful for me, but all things do not build up (confirm) (strengthen).
1 Timothy 4:3
They will forbid marrying, [and command] to abstain from food, which God created to be received with thanksgiving by those who believe and know the truth.

Their

1 Corinthians 8:7
Not all people know this. Some eat food offered to idols and their conscience being weak is defiled.
Hebrews 9:14
The blood of Christ did even more. Through the eternal Spirit he offered himself without blemish to God and cleansed your conscience from dead works. Now we can serve (worship) the living God.
Hebrews 10:22
let us draw near with a true heart in full assurance of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with pure water.

General references

Leviticus 7:19
The flesh that touches anything unclean shall not be eaten. It should be burned with fire. As for other flesh, anyone who is clean may eat such flesh.
Leviticus 10:10
You must learn the difference (distinction) between what is holy and what is not holy and between the clean and the unclean.
Leviticus 11:34
If water from that pottery touches any food, the food is unclean. Any liquid that you drink from that pottery is unclean.
Deuteronomy 14:3
Do not eat any detestable thing.
Acts 24:16
I exercise myself always, to have a conscience void of offense toward God and toward men.