Theists, provide your arguments for God.

[brewer]

That just means they have no argument.

They have an argument, it's just unsupportably bad.

[Ferrocyanide]

The observed inter-dependent of any parts of universe implied the changing form/qualities of parts of the universe that did not coming from each parts of universe itself independently. 
The changing form/qualities of those parts describing that there were previous attributes/qualities/conditions turned to later attributes/qualities/conditions. 
So, there was beginning of those parts. 
Hence, universe is not eternal. 
It started to form, hence there is starter/creator/designer.

Quite a lot of theists are under the impression that the Big Bang theory states that the universe began to exist.
Nope. It makes no such claim. No such data exist.

Yes, you can say that a proton began to exist. You can say that the Earth began to exist. You can say that over there, a photon began to exist.

These are all cases of transformation.
Matter transforming to energy. Energy transforming to matter.

So, there was beginning of those parts.
Hence, universe is not eternal.

Just because a thing has a beginning doesn’t mean that it was created from nothing.

It started to form, hence there is starter/creator/designer.

We don’t know what caused the Big Bang. The Big Bang event is just the rapid expansion of the universe.
The cause might be a black box, it might be an accordion, it could be some event that happened outside our universe (if there is an outside), it could be alien-gods.