WASHINGTON, D.C. – Facebook CEO Mark Zuckerberg faced questions from lawmakers about his company’s censorship of Catholic content during his two-day congressional hearing following the revelation that millions of Facebook users’ personal data had been compromised.

Zuckerberg apologized and said that the company “made a mistake” in blocking a Catholic theology degree advertisement by Franciscan University of Steubenville, when asked about it by Washington state Congresswoman Cathy McMorris Rodgers on the second day of questioning.

The ad, which featured a crucifix, was rejected by Facebook over Easter on the grounds that its content was “excessively violent” and “sensational.” Facebook later apologized, saying that the ad had been blocked erroneously and did not violate terms of service.

Zuckerberg on Wednesday emphasized the large number of ads that are reviewed daily by the Facebook team, saying, “I wouldn’t extrapolate from a few examples to assume that the overall system is biased.”

The tech CEO also expressed regret that he did not “take a broad enough view of our responsibility” to prevent tools from being used for harm, particularly with regard to “fake news, for foreign interference in elections, and hate speech, as well as developers and data privacy.”

RELATED: Barron tells Google religion’s the ultimate search engine

Senator Ted Cruz (R.-Texas) confronted Zuckerberg about alleged bias and censorship of political and religious content on the technology platform, saying Facebook “has blocked over two dozen Catholic pages” as well as conservative content “after determining their content and brand were, quote, ‘unsafe to the community.’”

In July 2017, CNA reported that Facebook blocked 25 Catholic pages in English and Portuguese. Facebook later apologized, saying the error was due to a malfunction rather than malicious intent. Earlier this year, another Catholic group said it was experiencing critical delays in approval of its fundraising content in support of vocations during the Christmas season.

Cruz continued to grill Zuckerberg over whether any Planned Parenthood or MoveOn.org ads had been removed. The Facebook CEO said that he was not aware of this ever occurring.

Pressed about bias, Zuckerberg said that “Facebook and the tech industry are located in Silicon Valley, which is an extremely left-leaning place,” but that he is committed to “making sure that we do not have any bias.”

Many lawmakers questioned Zuckerberg about his company’s policies for monitoring the ads and debates on its platform.

When asked to “define hate speech” by Senator Ben Sasse, Zuckerberg responded, “I think that this is a really hard question,” but reiterated his resolve to block efforts that spread hatred or violence.

Sasse continued, “There are some really passionately held views about the abortion issue on this panel today. Can you imagine a world where you might decide that pro-lifers are prohibited from speaking about their abortion views on your content — on your platform?”

“I certainly would not want that to be the case,” responded Zuckerberg, who went on to say that a technological shift toward using artificial intelligence to “proactively look at content,” will lead to “massive questions for society about what obligations we want to require companies to fulfill.”

RELATED: Church’s Silicon Valley envoy says questions, not answers, are key

The Facebook CEO was called to testify before Congress in the wake of scandals involving privacy violations and foreign interference in the 2016 elections.

Zuckerberg apologized repeatedly for the scandal involving the data-mining firm Cambridge Analytica, in which personal information from 87 million accounts was “improperly shared.”

Addressing these privacy concerns, Senator Dick Durbin asked Zuckerberg if he would be comfortable sharing the name of the hotel where he was staying.

When the CEO responded that he would not, Durbin replied, “I think that may be what this is all about: your right to privacy, the limits of your right to privacy and how much you give away in modern America in the name of, quote, ‘connecting people around the world.’”