The whole sentence is “ It is hard to hate up close, and the FBI could bring people up close.”
It is hard to maintain prejudiced hate, once you get to know the person.
The quote appears in a number of interviews and speeches by (2015 F.B.I Director) James Comey, where he discusses the problems with prejudices in the police force. His view is that a lot of the prejudices, against black Americans, from the police force - can be solved by having the police get closer to the communities they are meant to protect.
The idea is that if you have hateful views of a community, from being ignorant, that these can be solved by getting to know the community better. Being closer to the community (in emotional/relationship distance) helps you to see them as individuals and avoid applying prejudiced stereotypes to them.
I have to apologise for the lack of direct/dictionary references on this, as the phrase is not a widespread idiom - but it's meaning will be relatively clear to native speakers.