According to 1 John 4:20, anyone who says 'I love God' but hates his brother is what?

Answer: A liar

He is a liar, for anyone who does not love his brother, whom he has seen, cannot love God, whom he has not seen.

“If anyone says, “I love God,” but hates his brother, he is a liar. For anyone who does not love his brother, whom he has seen, cannot love God, whom he has not seen.”— 1 John 4:20 (BSB)