Who (or what), is responsible for the Big Bang

If the Big Bang did happen and God was not responsible for it, but yet was rather a random occurrence, then why hasn't it happened again (or happen all the time)? The fact that a "Big Bang" has only happened once would suggest that it is not a sporadic random occurrence, but rather an intentional (perhaps divine) action.

Some scientists believe that eventually all the matter will compact around itself again, and we will have a repeat cycle infinitely. It sounds like you already have an opinion, but with current technology, short of divine intervention we will never know for sure the answers to any of your questions.

Current hypotheses state that before the Big Bang happened, the place where universe had been had unexpectable and unimaginable physical laws and properties. As we can't prove what happened before the Big Bang, theories about what was before Big Bang are usually ignored to not over-complicate science with unprovable theories. This frankly doesn't give that big opportunity for churches to prove their beliefs.

A singularity. We have evidence of this. You have yet to provide any evidence of your God.

For thousands of years, people have said that their god was behind what they didn't understand -- life, lightning, stars, earthquakes, the origin of life, the world or the universe, etc. Positing a god to supposedly answer a question solves nothing. It just stops you from asking more questions.

There are many well-respected physicists, such as Stephen Hawking, Lawrence Krauss, Sean M. Carroll, Victor Stenger, Michio Kaku, Alan Guth, Alex Vilenkin, Robert A.J. Matthews, and Nobel laureate Frank Wilczek, who have created scientific models where the Big Bang and thus the entire universe could arise from nothing but a quantum vacuum fluctuation -- via natural processes.

In relativity, gravity is negative energy and matter is positive energy. Because the two seem to be equal in absolute total value, our observable universe appears balanced to the sum of zero. Our universe could thus have come into existence without violating conservation of mass and energy — with the matter of the universe condensing out of the positive energy as the universe cooled, and gravity created from the negative energy. When energy condenses into matter, equal parts of matter and antimatter are created — which annihilate each other to form energy. However there appears to be a slight imbalance to the process, which results in matter dominating over antimatter.