The metaphor Jesus was using was a sword for battle, since he was declaring he did not come to bring peace.
Matthew 10:35-37. It says that members of your family who don't accept Christ are your foes and further says that's because Jesus demands you love him more than them.
Love thy neighbor is a actually a law from the Old Testament (Leviticus 19:18). Jesus just repeated it. Since Christians never read the Old Testament, they assume Jesus came up with it.
It's generally accepted that the Jews considered "neighbors" to be their fellow Israelites. For example God commanded them to exterminate or enslave all Moabites, Canaanites, and any other "foreigners" they found in the Promised Land.
I haven't found anything in the New Testament that says non-believers are neighbors. There are verses that say they are foes.
I didn't really care! I'm just amazed at how some Christians drill the "You're going to HELL!" aspect of their religion yet others say "That's just a small part of Christianity. Don't worry about it." It looks to me like the idea of people suffering for all eternity for not having their Christian beliefs is exciting to some yet embarrassing to others.