Disclaimer: I don’t own the Terminator, because if I did I would be James Cameron, and Dark Angel would have never been cancelled.
It was a deep magic, in existence. It was a way to protect live, even against itself. For the terrible things that happen, have to happen, due to our own actions, a counter action happens, a way to bring balance. These counter actions are humans, who can change things, help save live. They can only exist if the events they are to prevent exist.
For John Connor to exist, Judgement day has to occur. His existence is proof that Judgement Day happens, and that Skynet will not prevail. John Connor exists due to a spasm in time, the universe protesting against the destruction of so much live. He tried to prevent the event that causes him to exist, because even while he is hope, he is human. Like Cassandra, he saw it all coming, the war, the death, but no one believed him. No one can bear to live with themselves, if they knew that would, and they didn’t try to prevent it.
You like? You hate? Please tell me.