Georges Lemaître is quite unknown in Czech society. Although he was one of the scientists who independently anticipated the expansion of the cosmos and later formulated one of the most important hypotheses of the twentieth century - the hypothesis of the Primavel Atom, generally known as the Big Bang Theory as well as he was the president of The Pontifical Academy of Sciences, there has been published almost nothing about him in the Czech Republic. What was Lemaître's life like? What does his hypothesis mean in the context of Christian astronomical discourse of last centuries? How was his mission of the priest linked with work in astrophysics and mathematics?