Was the Big Bang first proposed by a priest?

Yes. The idea that grew into the Big Bang theory came from Georges Lemaître. He was a Belgian physicist, and he was also a Catholic priest. In 1927 he proposed that the universe is expanding. In 1931 he suggested that it began from a single, dense starting point, which he called the primeval atom. The American Museum of Natural History says this idea of a beginning first appeared in scientific form in his 1931 paper.

People ask this for different reasons. A believer may feel proud, or may wonder if the Big Bang was a religious idea in disguise. A skeptic may be surprised, or may suspect the story has been polished. Both deserve the plain history, with its twists.

The twists matter. Lemaître was not the only builder. The Russian cosmologist Alexander Friedmann had found the same kind of math in 1922. Lemaître did not know it. His own 1927 paper went almost unnoticed. It was in French, in a little-read Belgian journal. Then Edwin Hubble published measurements of galaxies in 1929. His data and Lemaître’s paper won over most astronomers. In 2018, members of the International Astronomical Union voted to recommend a new name for the pattern: the Hubble–Lemaître law.

Lemaître’s faith and his science lived side by side in one person, but he kept them distinct on purpose. He spoke of two paths to truth, and he said his theory stayed outside any religious question. When Pope Pius XII praised the new cosmology in 1951 as a witness to creation, Lemaître was troubled. He had worked hard not to be seen as a priest using physics to argue for God.

So the fair answer is yes: a priest proposed it, and he refused to turn it into a sermon. Whether the universe was created is a different question, one we label Beyond science. You are welcome here, whatever you believe.