It says the reason women don't make up half of the company's technological and leadership positions is because of "genetic differences" in their preferences and abilities.
"These differences may explain why we don't see equal representation of women in tech and leadership," the engineer wrote. "We need to stop assuming that gender gaps imply sexism."
The author says the company's diversity efforts have "created a politically correct monoculture that maintains its hold by shaming dissenters into silence" and makes it easier for "extremist and authoritarian policies" to take root.
He says Google's efforts to achieve more equal gender and race representation - special programs for HBCUs for example, or coding camps for girls - have led to "discriminatory practices," specifically against conservatives.
In the essay, the author says he has received support from others in the company for "bringing up these very important issues," which others "would never have the courage to say or defend because of our shaming culture and the possibility of being fired."
The essay comes as the Mountain View, California, company has been trying to increase the stubbornly unbudging percentage of women and minorities in its ranks and is being investigated by the Labor Department for a disparity in pay between men and women.
Responding to the essay in a message to Google employees, Danielle Brown, the company's new vice president of diversity, integrity and governance, said the essay "advanced incorrect assumptions about gender."
"Diversity and inclusion are a fundamental part of our values and the culture we continue to cultivate," Brown said. "We are unequivocal in our belief that diversity and inclusion are critical to our success as a company, and we'll continue to stand for that and be committed to it for the long haul."
As The Washington Post's Jena McGregor wrote in March, just 1 per cent of Google's technology employees are black - a percentage that hasn't moved since 2014.
To become more diverse, McGregor wrote, "the company has expanded its recruiting to a broader range of schools, trains its workers on 'implicit biases' and re-examines résumés to make sure recruiters don't overlook diverse talent."
Slack engineer Erica Baker, whom CNBC called an "outspoken critic of systematic bias in the tech industry," said the engineer's diatribe was shocking but not surprising.
"Google has seen hints of this in the past, with employees sharing blog posts about their racist beliefs and the occasional internal mailing list question, 'innocently' asking if Black people aren't more likely to be violent," she wrote on her blog Saturday.
"The most important question we should be asking of leaders at Google and that they should be asking of themselves is this: Why is the environment at Google such that racists and sexists feel supported and safe in sharing these views in the company?"
Yonatan Zunger, a former senior Google employee, also took issue with the software engineer's post. He wrote on Medium that the essay shows a misunderstanding of the way Google tries to address the world's problems:
"Essentially, engineering is all about cooperation, collaboration, and empathy for both your colleagues and your customers. If someone told you that engineering was a field where you could get away with not dealing with people or feelings, then I'm very sorry to tell you that you have been lied to."
