1 John 4:20

If any one says, "I love God," and yet hates his brother, he is a liar; for he who does not love his brother whom he has seen, cannot possibly love God, whom he has not seen.

1 John 2:4

He who says, "I know Him," but does no continue obeying his commandments, is a liar,

1 John 2:9

He who says he is in the light, and hates his brother, is in darkness even until now.

1 John 3:17

But whoever has this world's goods, and beholds his brother in need, and shuts up his heart against him, how can the love of God continue to abide in him?

1 John 4:12

No man has ever gazed on God; but if we love one another, God ever abides in us, and his love is perfected in us.

1 John 2:11

But he who hates his brother is in the darkness, and is spending his life in the darkness, and does not know where he is going, because the darkness has blinded his eyes.

1 Peter 1:8

Him you love, though you have never seen him; in him you ever believe, though even now you see him not, and you are rejoicing with joy unspeakable and full of glory,

1 John 1:6

If we say, "We have partnership with Him," when we are passing our life in the darkness, we are lying and are not doing 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," but does no continue obeying his commandments, is a liar,
1 John 3:17
But whoever has this world's goods, and beholds his brother in need, and shuts up his heart against him, how can the love of God continue to abide in him?

Not

1 John 4:12
No man has ever gazed on God; but if we love one another, God ever abides in us, and his love is perfected in us.

General references

Matthew 22:40
"On those two commandments hang the whole law and the prophets."
Matthew 25:42
"for I was hungry, and you gave me no food; I was thirsty, and you gave me no drink;
John 13:35
By this shall all men know that you are my disciples, if you have love one for another."
John 14:15
"If you love me, you will obey my commandments,
Hebrews 13:1
Let brotherly love continue.