I have a question that I would like everybody to weigh in on. Jesus loves everyone from the day they are born but still some people don't cherish that and have hate in their hearts. Why????
There are evil spiritual influences. See Ephesians 6:11-13. There are evil influences exemplified in other people the formative learn from. There's basic vanity, selfishness that needs to be unlearned. Like somebody once said, if you want a child to turn out rotten, just leave them alone. We are predisposed to seek the world and the flesh. Turn on your TV, flip around and see how much God is there. Most adults have never left behind that fleshy baby, whose mantra is feed me.
People are also in love with their sin more, don't want righteousness raining on their vanity parade. See John 3:19-21. Without God drawing man, man would not even come to God. See Romans 3:10-18. Therefore, the predisposition of man is towards unrighteousness, evil. We must be born again, by the Holy Spirit, to have anything in the image of the love of God, in Christ Jesus. Until then, we are dead in trespasses and sin. See Ephesians 2:1-3.
An observation on your premise. There isn't a thin line between love and hate. This is a catchy little quip of the world and the flesh, and there may be a thin line between lust and hate. The world mistakes lust for love. Want proof? Listen to some songs on the radio. In truth, there's a gulf between Godly love and hate, as wide as the gulf between heaven and hell. Don't mistake lines from a romance novel with scripture truth.