Chicken and egg problem, which came first?
The evidence is present to exit from this conundrum, there is no need to be stuck in a loop. Instead there is a continuum of life. Eggs came before chickens -- and birds can be traced from fossils in the geological record back to therapods, egg laying 'dinosaurs'.
Evidence for evolution is found in the fossils showing that all life has evolved from the same archaic biological material (DNA) back in the Precambrian period.
Why would anyone want to deny evidence? Only because fossil evidence denies the need for a god.