I do not know that if Gould was an atheist or not but he was promoting a lie about the creation of the earth. I have to say that he was a genius, for when he saw that gradual evolution wasn't the answer, he came up with an alternative theory, punctuated evolution. Even so, his theory has not been proven yet, so it only remains a postulate. I believe in the "punctuated" postuate of Creation, that God created the universe out of nothing in the space six 24-hour days, by the word of his power, and all very good. I also like his statement about genius, the ability to see across manu fields and to make connections between them.
What was this "lie" about the creation of the Earth that Gould promoted?
Punctuated Equilibrium is not an alternative to evolution, rather it is complimentary. While gradualism is displayed in the fossil record, there is a relative dearth of "transitionals" in the fossil record. This does not mean there are no transitionals — there are — it simply means that transitionals are not as common as they should be. Punctuated Equilibrium postulates that in some cases evolution takes place rapidly in a few thousand generations rather than a few tens- or hundreds-of-thousands of generations. Because the former time frames are geologically relatively short the chances of the transition being recorded in the fossil record becomes increasingly small.
As for "proving" evolution, in science theories are never proven. They either explain the evidence or they are discarded. Evolution does wonders for explaining the fossil record and is supported by a preponderance of the evidence available.
What proof is there of God creating the Earth and all therein during one extremely hectic week? Geologists were the first to dispute a recent creation beginning in the 18th century when they actually started systematically and accurately dating rocks. Biologists started questioning the whole setup in the 19th century when they began studying the fossils of prehistoric critters and realized they were far too old to be accounted for in a recent creation. Astronomers followed later in the 19th century as measurements to the stars became more refined and accurate. Finally, physicists joined the band wagon when they determined that it was possible the Sun had been burning for more than a few hundred million years. So, you can see, it is not merely evolutionary biologists that have presented evidence against God's zapping it all into existence in six 24-hour days; indeed every scientific discipline has had a hand in burying that ancient belief.