If atheists need an evidence for god to believe in it, why don't they need evidence on the big bang theory?

It's good to be skeptical. That's what science is all about, but it's not good to be skeptical under the guise of religious indoctrination. That is dishonest.

On a side note, the Big Bang theory was developed by a Christian scientist.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.