The big bang theory suggests that the universe was created from a random explosion of gases, of which the universe is still expanding. Many people rejected this idea in the past because of their religious beliefs and it was seen as wrong and going against the idea of God's existence.
The Big Bang is a theory made by scientists which suggests the early development of the universe. Some people don't believe in this due to religion - they believe that God made the universe and there was no big bang. However, considering the evidence, the Big Bang Theory is possible.
Big bang theory is basically a hypothesis which was that all the universe's matter was compiled into a small dot no bigger than a full stop and this was under great pressure where it exploded releasing a lot of radiation and energy, including protons, neutrons etc.. But some people didnt believe that becuase many people where under the influence of catholic churrches and therefore followed the bibles teachings etc etc. But iqra got the rigth stuff