In a note sent to staff, and provided to CNN, Goldberg said Williamson's comments calling for women who have had abortions to be punished by death ran "contrary to The Atlantic's tradition of respectful, well-reasoned debate, and to the values of our workplace".
Goldberg had initially defended Williamson's hiring in a memo to staff last month, saying he likes to "give people second chances and the opportunity to change".
While it is important for outlets to give voice to many opinions, showcasing the range of views in the US, publications like The Atlantic and The New York Times, which famously fired Quinn Norton, picked to become the paper's lead opinion writer on tech, just six hours after hiring her, are giving a platform to extremists.
While Goldberg himself once trumpeted Williamson's hire from the National Review, the writer immediately drew outrage - particularly over a tweet in which he argued that women who had had an abortion should face the death penalty.
Those comments, all of which were public and made long before The Atlantic hired Williamson, were reiterated in a series of podcasts as well, Media Matters reported Tuesday. Williamson argued that current methods of execution, like lethal injection, are "too antiseptic" and that a punishment like "hanging" is more appropriate.
In his email, Goldberg wrote that The Atlantic did not fire Williamson for being pro-life, but rather because the magazine anxious his views and prior statements would result in a negative work atmosphere for female staff members who may have had an abortion.
"Kevin is a gifted writer, and he has been nothing but professional in all of our interactions".
The letter went on to say, "The tweet was not merely an impulsive, decontextualized, heat-of-the-moment post..."
In a letter to staff Goldberg stated: "The language he used in this podcast-and in my conversations with him in recent days-made it clear that the original tweet did, in fact, represent his carefully considered views". "But I have come to the conclusion that The Atlantic is not the best fit for his talents, and so we are parting ways".