1. Every effect has a cause.
2. The universe is an effect.
3. Therefore, the universe is caused.
Now, keep in mind this speaks of being, not becoming. Whether a being can cause its own becoming is a different question entirely. But that a being cannot cause its own being is self evident, for to cause its own existence, it would have to be prior to itself, which is absurd. Therefore since the universe is an effect, it had to have a cause that is outside of the universe that caused it to exist.
God is not subject to this, for God is not an effect.