1 John 1:8

If we claim to have no sinful practices [in our lives], we are self-deceived and are not being truthful about the matter.

James 3:2

For we all make mistakes in many areas [of life]. If anyone does not make a mistake in what he says, he is a perfect person, capable of keeping a tight rein on his whole life also.

1 John 2:4

The person who says, "I have come to know Him," but does not obey what He commands, is lying [by such a profession], and the truth [about the matter] is not in his heart.

Romans 3:23

for everyone has sinned and falls short of God's glory [i.e., His approval, or His perfect character].

1 Corinthians 3:18

No one should fool himself. If any person among you thinks he is smart, by human standards, he should become a "fool," so that he can become [really] wise.

Galatians 6:3

For any person who thinks he is someone [important], when he is really nothing, is self-deceived.

1 Timothy 6:5

[and] continual wranglings between people with corrupt minds, who are deprived of the truth. They think that [professing] godliness is a way to obtain [financial] gain.

2 Timothy 3:13

But evil people and impostors will go from bad to worse [in their behavior], deceiving people and being deceived by them.

James 1:22

But you should not deceive yourselves by just listening [to God's word] instead of doing what the word teaches.

James 1:26

If anyone considers himself to be religious and yet does not keep a tight rein on his tongue, this person is self-deceived and his religion is worthless.

2 Peter 2:13

They suffer wrong themselves for doing wrong to other people. They consider it [especially] pleasurable to carry on their drunken revellings, [even] during the daytime. They become blots and blemishes [i.e., like spoiled food] in your fellowship meal, as they revel in their deceitful behavior.

1 John 1:6

If we claim to share a relationship with God and yet live in darkness [i.e., in a sinful way], we are lying and are not living a truthful life.

1 John 1:10

If we claim that we have not committed sins, we are [in effect] calling God a liar [i.e., because He says we have] and His word [i.e., the real truth about the matter] is not in our hearts.

1 John 3:5-6

But, you [should] know that Christ appeared [on earth] to take away [our] sins, and that there is no sin in His life [See II Cor. 5:21].

2 John 1:2

[We all love you] because of the truth which continues to live in our hearts and will be with us forever.

3 John 1:3

For I was very happy when some of the brothers came and told me that you are being [faithful] to the truth [i.e., the word of God], and that you are living according to it, [as well].

Treasury of Scripture Knowledge

Summary

If we say that we have no sin, we deceive ourselves, and the truth is not in us.

General references

Bible References

Say

1 John 1:6
If we claim to share a relationship with God and yet live in darkness [i.e., in a sinful way], we are lying and are not living a truthful life.
1 John 3:5
But, you [should] know that Christ appeared [on earth] to take away [our] sins, and that there is no sin in His life [See II Cor. 5:21].
Romans 3:23
for everyone has sinned and falls short of God's glory [i.e., His approval, or His perfect character].
James 3:2
For we all make mistakes in many areas [of life]. If anyone does not make a mistake in what he says, he is a perfect person, capable of keeping a tight rein on his whole life also.

We deceive

1 Corinthians 3:18
No one should fool himself. If any person among you thinks he is smart, by human standards, he should become a "fool," so that he can become [really] wise.
Galatians 6:3
For any person who thinks he is someone [important], when he is really nothing, is self-deceived.
2 Timothy 3:13
But evil people and impostors will go from bad to worse [in their behavior], deceiving people and being deceived by them.
James 1:22
But you should not deceive yourselves by just listening [to God's word] instead of doing what the word teaches.
2 Peter 2:13
They suffer wrong themselves for doing wrong to other people. They consider it [especially] pleasurable to carry on their drunken revellings, [even] during the daytime. They become blots and blemishes [i.e., like spoiled food] in your fellowship meal, as they revel in their deceitful behavior.

General references

Hebrews 8:12
For I will be merciful to their wickedness [i.e., by forgiving them] and I will not remember their sins anymore."