My father espoused Darwinist evolution and “The Big Bang” theory. Challenging when I knew God from when in diapers. I pointed out that in the NICU, we never saw improvements, only defects and deformities. We never saw any “good” mutations. He had not come backs for that.
Not challenging your religious beliefs, but Darwin did not think that natural genetic mutations would always be good. He said that if they were good then they would tend to become dominant and the species would naturally improve.
He based his theories on direct, first hand observations.