What Is The Meaning Of 'I will see thee at Philippi'.

“I will see thee at Philippi” is a line from Shakespeare's "Julius Caesar" Caesar's ghost to Brutus. Brutus asks the ghost “What and whence art thou?” Caesar's ghost replies, “Thy evil spirit, Brutus: I shall see thee at Philippi”. Brutus and Cassius plot to march to Philippi to challenge Mark Antony and Octavius. And Philippi in the play is the place of the final confrontation for those who supported the Roman Republic. Brutus will meet his death in the battle, and will indeed “see” Caesar in the afterlife. Brutus will meet his death in the battle, and and then “see” Caesar again in the afterlife.

I'm a little confused by those lines. I thought at first it meant that the two will be again, and be reunited in friendship in the afterlife. But I keep reading it is more of a threat. Are they reunited in friendship when they die? And what was the ancient Roman afterlife like? Did it have reward and punishment? Was Shakespeare actually talking about the Christian afterlife?

Like I was telling some people, I was sharing this quote and the meaning behind it with a Facebook prison Shakespeare group because I think it talks about things like ultimate forgiveness and things working out in the end. But does it?