Because of the following reason:If something has always existed, it doesn’t need a creator. Think about the computer you are using to read this article. If your computer had always existed it wouldn’t need a creator.
The obvious answer is NO, he would not fire.
The only way the sniper can shoot is if someone along the chain has the final authority to give that command.
In the same way God created the universe, if we were then to ask who created God? And then ask who created the creator of God? and then who created that creator and so on and so on, then there would be no universe at all in the same way the sniper would not be able to shoot! This proves that the universe must have a creator who is uncreated – God.