1 John 4:20

If a man says, I love God, yet he hates his brother, he is a liar! He who does not love his brother, whom he has seen, cannot love God whom he has not seen.

1 John 2:4

He who says: I know him, and does not obey his commandments is a liar! The truth is not in him.

1 John 2:9

He who says he is in the light and hates his brother is still in the darkness!

1 John 3:17

Whoever has this world's goods and sees his brother in need, and shuts up his compassion from him, how does the love of God dwell in him?

1 John 4:12

No one has seen God at any time! If we love one another, God lives with us, and his love is perfected (accomplished) (matured) through us.

1 John 2:11

But he who hates his brother is in the darkness, and walks in the darkness. He does not know where he goes because the darkness has blinded his eyes.

1 Peter 1:8

You love him without seeing him. Though you do not see him, you believe in him. Full of glory, you rejoice greatly with indescribable joy.

1 John 1:6

If we say we have fellowship with him and walk in the darkness, we lie, and do not live (practice) the truth.

Treasury of Scripture Knowledge

Summary

If a man say, I love God, and hateth his brother, he is a liar: for he that loveth not his brother whom he hath seen, how can he love God whom he hath not seen?

Bible References

A man

1 John 2:4
He who says: I know him, and does not obey his commandments is a liar! The truth is not in him.
1 John 3:17
Whoever has this world's goods and sees his brother in need, and shuts up his compassion from him, how does the love of God dwell in him?

Not

1 John 4:12
No one has seen God at any time! If we love one another, God lives with us, and his love is perfected (accomplished) (matured) through us.

General references

Matthew 22:40
The law and the prophets are based on these two commandments.
Matthew 25:42
I was hungry and you did not feed me. I was thirsty and you did not give me drink.
John 13:35
All men will know that you are my disciples if you have love for one another.
John 14:15
If you love me, you will keep (obey) my commandments!
Hebrews 13:1
You should continue to love one another as brothers.