The point is that he's coming back to get/reward all those on his side (not religion specific}. Either you are with him or against; him no innocent bystanders. He's not coming to PROVE anything. Who's opinion does he want/need? Interfere with his will-You are destroyed.
Come on, take a step back and re-read this. It just sounds very very silly and childish. I'm not saying you are being childish, but that this kind of statement is childish.
If God is all present, all powerful and all knowing, why does he need to come back and reward some people and punish others. If God is all love, why wouldn't he forgive those who didn't believe in him. Why wouldn't he punish those who do believe for failing to convert those that didn't?
These "my way or the highway" type statements don't sound like the word of God. They sound like the word of men in positions of power who want to exert that power and influence over others.
This is why organized religion has such a bad reputation. Clearly, whoevers been feeding you this stuff is doing so because they want influence over you, they want you to a) give them money or b) do what they tell you to do.
God would not need to use threats to get his point across