Picture an abusive relationship. A husband abuses his wife, yet the wife continues to defend him as a person, and even his abusive actions. She refuses to leave or take action, whether out of fear, or out of a genuine belief that he is right to behave as he is.
If someone you love was ever in the position of such a wife, it should absolutely break your heart to see this happening, and you should do everything in your power to convince her to leave her husband and have him prosecuted. Tragically, it's often the case that abuse victims reject your advice, even stubbornly, and with irrational reasoning.
Tell me, how much would you hate such a woman? If your answer is "I wouldn't hate her at all", good! That is the correct answer. You should burn with love and compassion for such people, no matter how irrational, and where possible, you should protect them.
Why, then, is it so difficult for us, as Christians, to love unbelievers we encounter in our day to day lives? We often look at unbelievers and become no better than them in our conduct. He's mocking God? Let's mock him! He's reviling Christians? Let's revile him! Let's get really emotionally charged and take out all our rage on this unbeliever and make him really hate Christians, and therefore have reason to hate our God! No! How about this: Rather than thinking "I'm going to win an argument with you" how about we instead think "I'm going to try to win you!" Rather than thinking "This one deserves to be taken down a peg or two", how about we think "it would be the greatest tragedy if this person does not take his place in God's kingdom"? Instead of telling people to go to Hell, why don't we plead with them not to?
Unbelievers are not our real enemies. Unbelievers are trapped in an abusive relationship with sin, and whether out of fear or deceit, they aren't leaving. When you have spent 20billion years in Heaven, you won't still be salty about that one internet troll, but if he is not in Heaven, he won't be too happy about it. When you have lived with God for 70trillion years, that crazy woman who called you a Bible thumping moron won't even cross your mind, but if she is not also dwelling with God, you will certainly cross hers. The very last words of Stephen the Martyr show his own love for those who stoned him to death. If Stephen, the Apostles, and even Jesus can love Paul, after all that he did, we should absolutely repent of every time we have failed to love the lost. Then we should love them all the more.