New Revised Standard Version
But whoever hates another believer is in the darkness, walks in the darkness, and does not know the way to go, because the darkness has brought on blindness.

Contemporary English Version
If we hate others, we are living and walking in the dark. We don't know where we are going, because we can't see in the dark.

New American Bible
Whoever hates his brother is in darkness; he walks in darkness and does not know where he is going because the darkness has blinded his eyes.

Douay-Rheims Bible
But he that hateth his brother is in darkness and walketh in darkness and knoweth not whither he goeth: because the darkness hath blinded his eyes.

But he that hateth his brother is in darkness and walketh in darkness and knoweth not whither he goeth: because the darkness hath blinded his eyes.

he that.

1 John 2:9 He that saith he is in the light and hateth his brother is in darkness even until now.

John 12:35 Jesus therefore said to them: Yet a little while, the light is among you. Walk whilst you have the light, and the darkness overtake you not. And he that walketh in darkness knoweth not whither be goeth.

Titus 3:3 For we ourselves also were some time unwise, incredulous, erring, slaves to divers desires and pleasures, living in malice and envy, hateful and hating one another.

and walketh.

Proverbs 4:19 My son, hearken to my words, and incline thy ear to my sayings.

John 12:35 Jesus therefore said to them: Yet a little while, the light is among you. Walk whilst you have the light, and the darkness overtake you not. And he that walketh in darkness knoweth not whither be goeth.

because.

John 12:40 He hath blinded their eyes and hardened their heart, that they should not see with their eyes, nor understand with their heart and be converted: and I should heal them.

2 Corinthians 3:14 But their senses were made dull. For, until this present day, the selfsame veil, in the reading of the old testament, remaineth not taken away (because in Christ it is made void).

2 Corinthians 4:4 In whom the god of this world hath blinded the minds of unbelievers, that the light of the gospel of the glory of Christ, who is the image of God, should not shine unto them.

Revelation 3:17 Because thou sayest: I am rich and made wealthy and have need of nothing: and knowest not that thou art wretched and miserable and poor and blind and naked.