The father of the big bang theory himself was a Jesuit Priest doing science in the Vatican. Geogres Lamaitre. The term "big bang" was to be applied later, he described it as a "primordial atom"
It may be of interest that the big bang was resisted because it implies a moment of creation, which is a rather difficult thing to reconcile with atheism. Lamaitre himself assured naturalistic colleagues that they could find a way to reconcile the theory with naturalism...although for myself I find such reconciliation very problematic.
Oh there you go AndyTheBear, you ignorant twit...he was not in the vatican when he came up with the theory.