Titus 1:15

To the pure all things are pure; but to the defiled and unbelieving nothing is pure; but both their mind and their conscience have become defiled.

Romans 14:20

Do not, for the sake of food, overthrow the work of God. All things, indeed, are clean; but it is evil to him who eats with offense.

Romans 14:23

And he who doubts is condemned, if he eat, because he eats not of faith; and all that is not of faith is sin.

Romans 14:14

I know, and have been persuaded in the Lord Jesus, that nothing is unclean of itself: except that to him who accounts anything to be unclean, to him it is unclean.

Matthew 15:18

But the things that proceed out of the mouth come forth out of the heart; and these defile the man.

Acts 10:15

And a voice came to him again, a second time, "What God cleansed, count not common."

Luke 11:39-41

But the Lord said to him, "Now ye, the Pharisees, cleanse the outside of the cup and the dish; but your inward part is full of extortion and wickedness.

1 Corinthians 6:12-13

All things are lawful for me; but all are not profitable. All things are lawful for me; but I will not be brought under the control of any.

1 Corinthians 8:7

But this knowledge is not in all; but some, by familiarity with the idol even until now, eat it as an idol-sacrifice; and their conscience, being weak, is defiled.

1 Corinthians 10:23

All things are lawful, but not all things are profitable; all things are lawful, but not all things build up.

1 Corinthians 10:25

Whatsoever is sold in the market eat, asking no question because of conscience;

1 Corinthians 10:31

Whether, therefore, ye eat or drink, or whatsoever ye do, do all to the glory of God,

1 Corinthians 11:27-29

Therefore, whosoever eats the bread or drinks the cup of the Lord unworthily, shall be guilty of the body, and blood of the Lord.

1 Timothy 4:3-4

forbidding to marry, and commanding to abstain from foods, which God created for reception with thanksgiving by those who believe and have full knowledge of the truth.

1 Timothy 6:5

wranglings of men corrupted in mind and bereft of the truth, supposing godliness to be a source of gain.

Hebrews 9:14

how much more shall the blood of Christ, Who through the Eternal Spirit offered Himself without blemish to God, cleanse your conscience from dead works to serve the living God?

Hebrews 10:22

let us approach with a true heart in full assurance of faith, having had our hearts sprinkled from an evil conscience, and our body 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.

General references

Bible References

The pure

Luke 11:39
But the Lord said to him, "Now ye, the Pharisees, cleanse the outside of the cup and the dish; but your inward part is full of extortion and wickedness.
Acts 10:15
And a voice came to him again, a second time, "What God cleansed, count not common."
Romans 14:14
I know, and have been persuaded in the Lord Jesus, that nothing is unclean of itself: except that to him who accounts anything to be unclean, to him it is unclean.
1 Corinthians 6:12
All things are lawful for me; but all are not profitable. All things are lawful for me; but I will not be brought under the control of any.
1 Corinthians 10:23
All things are lawful, but not all things are profitable; all things are lawful, but not all things build up.
1 Timothy 4:3
forbidding to marry, and commanding to abstain from foods, which God created for reception with thanksgiving by those who believe and have full knowledge of the truth.

Their

1 Corinthians 8:7
But this knowledge is not in all; but some, by familiarity with the idol even until now, eat it as an idol-sacrifice; and their conscience, being weak, is defiled.
Hebrews 9:14
how much more shall the blood of Christ, Who through the Eternal Spirit offered Himself without blemish to God, cleanse your conscience from dead works to serve the living God?
Hebrews 10:22
let us approach with a true heart in full assurance of faith, having had our hearts sprinkled from an evil conscience, and our body washed with pure water,

General references

Acts 24:16
In this I myself also am striving always to have a conscience void of offense toward God and men.