When Representative Mike Johnson of Louisiana wanted to make the case against abortion rights last year during a Capitol Hill committee hearing, he grilled a witness in graphic fashion.

“Do you support the right of a woman who is just seconds away from birthing a healthy child to have an abortion?” he asked at a Judiciary Committee hearing.

When the witness, Dr. Yashica Robinson, a board member for Physicians for Reproductive Health, responded that such a situation had never occurred, Mr. Johnson only doubled down.

“Never happened in your practice, ma’am,” Mr. Johnson fired back. “But it happens. How about if a child is halfway out of the birth canal? Is an abortion permissible then?”

The exchange reflected the lawmaker’s deeply conservative views, particularly on social issues, and his tendency to express them in inflammatory ways.

Mr. Johnson, the evangelical Christian who won the speakership on Wednesday with the unanimous support of House Republicans, has also spoken out sharply against homosexuality, calling it “inherently unnatural” and a “dangerous lifestyle” and linking it to bestiality, according to opinion essays unearthed on Wednesday by CNN.

“Experts project that homosexual marriage is the dark harbinger of chaos and sexual anarchy that could doom even the strongest republic,” he wrote in one such article in 2004.

The views are sharply at odds with those of most Americans, according to opinion polls that have found the public is broadly supportive of gay rights. Mr. Johnson’s abrupt rise to the speaker post this week in the depressed and divided House Republican conference underscores the rightward lurch of the G.O.P., which dumped his more mainstream predecessor, Representative Kevin McCarthy of California.

“If you don’t think that moving from Kevin McCarthy to MAGA Mike Johnson shows the ascendance of this movement and where the power in the Republican Party truly lies, then you’re not paying attention,” Representative Matt Gaetz, the Florida Republican who engineered Mr. McCarthy’s downfall, said in an interview on Steve Bannon’s “War Room” podcast.

Elected to Congress in 2016, Mr. Johnson, a lawyer and former chairman of the conservative Republican Study Committee, has never led a powerful committee in Congress or served in the top tier of House leadership. Democrats immediately pounced on the pivotal role he played in congressional efforts to overturn the 2020 election. (As a loyal supporter of former President Donald J. Trump, he has continued to use a podcast he hosts with his wife, a licensed pastoral counselor, to rail against the prosecution of Mr. Trump for his efforts to interfere in the 2020 election.)

But even more than his election denialism, Mr. Johnson’s political career has been defined by his religious views.

“I don’t believe there are any coincidences,” he said on Wednesday in his first speech on the House floor as speaker, adding: “I believe that God has ordained and allowed each one of us to be brought here for this specific moment in this time. This is my belief.”

He added that his wife “spent the last couple weeks on her knees in prayer to the Lord, and she’s a little worn out.”

Mr. Johnson, the son of a firefighter and the first in his family to graduate from college, was 12 when his father was burned and disabled in the line of duty.

“All I ever wanted to be when I grew up was the chief of the fire department in Shreveport,” Mr. Johnson said Wednesday. But the explosion that harmed his father, he said, “changed all of our trajectories.”

In Congress, Mr. Johnson has voted for a national abortion ban and co-sponsored a 20-week abortion ban, earning him an A-plus rating from the anti-abortion group Susan B. Anthony Pro-Life America. After the Supreme Court voted to overturn Roe v. Wade in June last year, he celebrated.

He said that millions of unborn children had lost their lives because of what he called a “legal fiction that the Supreme Court foisted upon this country” and said that “God will bless us” for the court’s decision.

Last year, Mr. Johnson introduced a bill that prohibited the use of federal funds for providing education to children under 10 that included L.G.B.T.Q. topics — a proposal that critics called a national version of Florida’s “Don’t Say Gay” law. Mr. Johnson called the legislation “common sense.”

He also opposed legislation to mandate federal recognition for same-sex marriages — a bill that passed with strong bipartisan support in both the House and the Senate.

In the years before he arrived in Congress in 2017, Mr. Johnson worked as an attorney and spokesman for the anti-abortion-rights and anti-gay group Alliance Defense Fund — now called the Alliance Defending Freedom. During that time, he expressed some of his hard-line views in editorials in the local newspaper in his hometown of Shreveport, La.

Writing in 2004 in support of a state amendment banning same-sex marriage, he asserted that without it, “There will be no legal basis to deny a bisexual the right to marry a partner of each sex, or a person to marry his pet.”

Mr. Johnson was only able to emerge as his party’s nominee for speaker this week after three other G.O.P. nominees before him were unable to rally enough support. It was unlikely to have happened in any other scenario.

Representative Steve Scalise of Louisiana, the No. 2 House Republican and the first to be nominated for speaker following Mr. McCarthy’s ouster, was ultimately seen as insufficiently pro-Trump by too many of his colleagues.

Representative Jim Jordan of Ohio, a founder of the hard-right House Freedom Caucus and someone Mr. Johnson has described as a mentor, was the next member to be elected speaker designate in a secret ballot. He had Mr. Trump and the far right in his corner, but ultimately failed to win over more centrist members of his party who steadfastly refused to support him.

Representative Tom Emmer of Minnesota, the majority whip and the third candidate for the speakership, had the biggest problems of any of the speaker-designates that preceded him: the hard-right wing of the party rose up to oppose him and former President Donald J. Trump branded him a “globalist RINO.”

Mr. Johnson’s quick ascent came when members of the conference were worn down and ready to accept someone whom they did not view as an obvious choice or the party’s natural leader in waiting. Instead, he cleared a lowered bar: They view him as someone sufficiently conservative and who they do not personally despise.

Mr. Johnson’s hallmark in Congress has been combining his hard-line views with a gentle personal style. That was on display on Wednesday, when he vowed to try to find common ground with Representative Hakeem Jeffries of New York, the minority leader.

“I know we see things from different points of view, but I know in your heart you want to do what’s right, so we’ll find common ground there,” he said.

To show support for racial equality, Mr. Johnson in the past has told audiences that he and his wife adopted a Black teenager they met through an evangelical youth group — like the movie “The Blind Side” but without the N.F.L. prospects, he has quipped.

He once shared the story with a mostly Democratic audience at a congressional hearing on slavery reparations, and he was surprised to hear boos as he spoke, he later recounted to the Council for National Policy, an assembly of conservative donors known for its strict secrecy.

“I had my feelings surgically removed back in the ’80s,” he joked, according to a recording of the event, and then suggested the hearing had been packed with Black Panthers who disapproved of the mixing of races. (The Black Panther Party dissolved decades ago.)

On Wednesday, Mr. Johnson was toiling to help Republicans turn the page from the chaos of the past few weeks. He said there would be none of the typical celebrations that accompany the election of a new speaker.

Instead, he moved quickly to bring up a resolution expressing solidarity and support for Israel. His next order of business, he said, would be addressing what he called the country’s “broken border” with Mexico. He made no mention of the impeachment inquiry into President Biden, or of the impending government shutdown that will begin next month if Congress fails to pass legislation to keep the government funded.

“These last few weeks probably look like total chaos, confusion, no end in sight,” Mr. Emmer, who tried and failed to become speaker, said on Wednesday. “But from my perspective, this is one of the greatest experiences of the recent history of our republic.”

Steve Eder contributed reporting.