The cosmological argument
Since Physicalism requires that every effect has a cause, we can say:
1. Whatever begins to exist has a cause.
2. The Universe began to exist
3. Therefore the Universe has a cause.
Premise 2 can be supported by evidence that the Universe began to exist at the Big Bang and also, if the second law of thermodynamics is true, a Universe which had been in existence for ever would have experienced an entropy death.
To avoid an infinite regress, the cause of the Universe must transcend material in some way and be spaceless, timeless, immaterial and unimaginably powerful. In other words something like God.
We only know of two entities which are spaceless and immaterial. One is the abstract idea of entities such as numbers, the other is mind or personhood. Abstract ideas cannot cause anything so it follows from this that God is a person (a being with consciousness and intention), not just an impersonal force.