John declared simply,

“He who says he is in the light, and hates his brother, is in darkness until now” (1 John 2:9).

He gave no qualifiers. He just stated the truth: If you claim to live in the light while at the same time hating your brother, then you are still in the darkness.

Therefore, repent of the hatred, and love your brother. That does not mean you have to agree with him, truly, other Bible passages show that you cannot agree with somethings, such as his sin, or whatever, nevertheless, you still have to seek his good will, even as the Father sought our good will when nothing about us agreed with Him!