Cause and effect is an emergent property of the universe
Furthermore, in physics, we have events that are uncaused. Even if the universe came into existence and had a beginning, it does not follow that it must have had a cause proceeding it
We don't know what happened close to the big bang.
There are many models which claim the universe never came into existence, something was always there ( Steinhardt Turok Model, conformal cyclical cosmology, loop quantum cosmology )
There's also the big bounce cosmology
To sum it up, we are still exploring, you believers should also wait and not rush to any conclusions
As for the existence of God. If God exists, he is unlike anything your holy books mention. He most certainly doesn't want us to worship him 5 times a day, he most certainly isn't obsessed with a figure from 7th century Arabia. Likewise for Christians, Hindus and Sikhs. Your beliefs are too primitive and crude.