20 If a man says, “I love God,” and hates his brother, he is a liar; for he who doesn’t love his brother whom he has seen, how can he love God whom he has not seen?
1 John 4:20 Cross References - WEB
1 Peter 1:8
8 whom, not having known, you love. In him, though now you don’t see him, yet believing, you rejoice greatly with joy that is unspeakable and full of glory,
1 John 1:6
6 If we say that we have fellowship with him and walk in the darkness, we lie, and don’t tell the truth.
1 John 2:4
4 One who says, “I know him,” and doesn’t keep his commandments, is a liar, and the truth isn’t in him.
1 John 2:9
9 He who says he is in the light and hates his brother is in the darkness even until now.
1 John 2:11
11 But he who hates his brother is in the darkness, and walks in the darkness, and doesn’t know where he is going, because the darkness has blinded his eyes.
1 John 3:17
17 But whoever has the world’s goods and sees his brother in need, then closes his heart of compassion against him, how does God’s love remain in him?
1 John 4:12
12 No one has seen God at any time. If we love one another, God remains in us, and his love has been perfected in us.