This document goes through the historical estimates of the age of the Earth, starting with Comte du Buffon in 1779 getting 75,000 years. 80 some years later, Lord Kelvin extended this to about 20 million years old. A fun quote from Kelvin's wikipedia page:
Thomson (Lord Kelvin) remained a devout believer in Christianity throughout his life; attendance at chapel was part of his daily routine. He saw his Christian faith as supporting and informing his scientific work
A fun fact about Cosmology is that an embarrassing thing happened in the 1900s is that the age of the Earth according to geology was older than the age of the Universe (by our first estimates of the Hubble constant). This also happened with some stars where the age of some stars was older than the universe. The remarkable thing and beautiful thing about science is that all the dates converged on a consistent date as more information came in. You would think that if science was wrong, the dates would get less and less consistent.