Because there had to be an uncaused cause. An impersonal cause would require a spontaneous arising of order. Also, the universe always existing is impossible because, if the universe is infinite, that means it has already existed for infinity. Therefore, there are 2 objections we must raise when we are told the universe is infinite.
1. Why hasn't the energy run out by now, according to the 2nd law of thermodynamics?
2. If the universe is infinite, that would mean you would have to cross infinity to get to this point. That is impossible. If there is no first event, then there can be no second or third because infinity is logically impossible in the natural world. God, not being constrained by the natural laws of the universe, exists outside of space and time and therefore does not need to exist "for infinity" for us to be here. He is the uncaused cause. Again, there must have been an uncaused cause because you can't have an infinite regression of causes.
Something that does not exist cannot bring something into existence, so the idea that the universe brought itself into existence has been realized to be absurd. Now it is time to realize the absurdity of an infinite universe. If there was not a personal cause, a decision, in the past, that brought us to this point, then we cannot exist. Watch the video in my above post.