Everything that begins to exist must have a cause.
The Universe began to exist at some point in time, it follows that the universe should have a cause.
What are the main characteristics of the universe? Time, Space and Matter. If there was no universe, there would have been none of these i.e. time or space or matter.
Logically it follows that whatever caused the universe should be outside of time, space and matter for it to create an universe. It should also be incredibly powerful and wise to create this universe.
So basically the cause for our universe is someone/something that is timeless, spaceless, non-material and has unimaginable power and wisdom.
I leave you to answer what this “cause” can be.
Genesis 1:1 In the beginning, God…..