Titus 1:15

All things truly pure to the pure: and to the defiled and unbelieving nothing pure; but also their mind and consciousness are defiled.

Romans 14:20

Not for sake of food destroy thou the work of God. Truly all things clean; but evil to the man eating by offence.

Romans 14:23

And he being judged if he eat, has been condemned for not of faith; and everything not of faith is sin.

Romans 14:14

I know and am persuaded in the Lord Jesus, that nothing common by itself; except to any one reckoning to be common, to that one it is common.

Matthew 15:18

But the things going forth out of the mouth come from the heart, and these pollute the man.

Acts 10:15

And a voice again of a second time to him, What things God cleansed, do not thou make common.

Proverbs 21:4

Lifting up the eyes and enlarging the heart, the light of the unjust is sin.

Haggai 2:13

And Haggai will say, If the unclean of soul shall touch upon any of these, shall it be unclean? and the priests shall answer and say, It shall be unclean.

Zechariah 7:5-6

Say to all the people of the land, and to the priests, saying, When ye fasted and mourned in the fifth and in the seventh, and this seventy years, fasting, fasted ye to me, me?

Luke 11:39-41

And the Lord said to him, Now ye Pharisees cleanse the outside of the cup and trencher; and your inside is full of plunder and wickedness.

1 Corinthians 6:12-13

All things are lawful to me, but all are not profitable: all are lawful to me, but I will not be exercised by power under any.

1 Corinthians 8:7

But not in all, knowledge: and some with consciousness of the idol even till now eat as a sacrifice to idols: and their consciousness being weak is contaminated.

1 Corinthians 10:23

All things are lawful to me, but all are not profitable: all things are lawful to me, but all build not the house.

1 Corinthians 10:25

Every thing being sold in the market, eat, ye, interrogating nothing through consciousness:

1 Corinthians 10:31

Whether therefore ye eat, whether ye drink, or what ye do, do ye all things to the glory of God.

1 Corinthians 11:27-29

Therefore whoever should eat this bread, and drink the cup of the Lord, unworthily, shall be liable to the penalty of the body and blood of the Lord.

1 Timothy 4:3-4

Hindering to marry, to keep from victuals which God created for participation, with thanks, for the faithful and them knowing the truth.

1 Timothy 6:5

Unprofitable occupations of men corrupted in mind, and deprived of the truth, thinking gain to be devotion: be separated from such.

Hebrews 9:14

How much more shall the blood of Christ, who by the eternal Spirit offered himself blameless to God, purify your consciousness from dead works to serve the living God?

Hebrews 10:22

Let us approach with a true heart in complete certainty of faith, having our hearts besprinkled from an evil consciousness, and having 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
And the Lord said to him, Now ye Pharisees cleanse the outside of the cup and trencher; and your inside is full of plunder and wickedness.
Acts 10:15
And a voice again of a second time to him, What things God cleansed, do not thou make common.
Romans 14:14
I know and am persuaded in the Lord Jesus, that nothing common by itself; except to any one reckoning to be common, to that one it is common.
1 Corinthians 6:12
All things are lawful to me, but all are not profitable: all are lawful to me, but I will not be exercised by power under any.
1 Corinthians 10:23
All things are lawful to me, but all are not profitable: all things are lawful to me, but all build not the house.
1 Timothy 4:3
Hindering to marry, to keep from victuals which God created for participation, with thanks, for the faithful and them knowing the truth.

Their

1 Corinthians 8:7
But not in all, knowledge: and some with consciousness of the idol even till now eat as a sacrifice to idols: and their consciousness being weak is contaminated.
Hebrews 9:14
How much more shall the blood of Christ, who by the eternal Spirit offered himself blameless to God, purify your consciousness from dead works to serve the living God?
Hebrews 10:22
Let us approach with a true heart in complete certainty of faith, having our hearts besprinkled from an evil consciousness, and having our bodies washed with pure water.

General references

Leviticus 7:19
And the flesh which shall touch upon any unclean thing shall not be eaten; it shall be burnt in fire: and of all clean flesh, the flesh shall be eaten.
Leviticus 10:10
And to separate between the holy and between the unholy, and between the unclean and between the clean:
Leviticus 11:34
From all food which shall be eaten which water shall come upon it, shall be unclean: and all drink which shall be drank from every vessel shall be unclean.
Deuteronomy 14:3
Thou shalt not eat any abomination.
Acts 24:16
And in this I myself attend carefully, to have a conscience unhurt towards God and men always.