America has a problem believing women and girls.

How else to explain the sickening spectacle of 156 women in a Michigan courtroom this past week facing down an abuser everyone — even their own parents — believed instead of them. The sentencing of former USA Gymnastics doctor Larry Nassar was a breathtaking display of the doubt and dismissal that so often greet women and girls when they report being molested or raped or harassed.

It is true Nassar was a determined predator, but his success depended on a nation of co-conspirators well versed in discrediting women. Our man-believing, woman-doubting world enabled a gold-plated sexual assault ring.

This should shake us to the core. Girls as young as 6 years old were forced to keep getting “treatments” by a doctor who repeatedly molested them, sometimes right in front of their parents. Those gymnasts, after being relentlessly abused by that man, performed flips and jumps and twists for the world’s delight, smiling and sparkly on the outside while their insides probably felt something like broken glass.

It was sexual slavery played out right before us in Olympic broadcasts anchored by the now-fired-for-sexual-misconduct Matt Lauer.

At least 14 officials at Michigan State University were told Nassar was a predator. The father of one of the survivors, Kyle Stephens, killed himself after believing Nassar over his daughter, when she described the brazen sexual abuse that took place during house calls to her childhood home. None of those officials believed it.

On Wednesday night, just hours after Nassar was sentenced to 40 to 175 years in prison, Michigan State’s president, Lou Anna Simon, resigned. Still to come: Investigations of USA Gymnastics and U.S. Olympic Committee that ought to reveal just how many people knew about what Nassar was doing and chose to ignore it.

“What does it say about our society when victims do come forward, and they are automatically met with skepticism and doubt, treated as liars until proven true?” asked the prosecutor, assistant attorney general Angela Povilaitis.

How many times does this have to happen?

Bill Cosby. More than 50 women have come forward since Andrea Constand first filed a police report in 2005.

Harvey Weinstein. More than 80 women have told their stories about sexual assault a dozen years after Courtney Love told TV cameras in 2005: “If Harvey Weinstein invites you to a private party in the Four Seasons, don’t go.”

R. Kelly. The 50-year-old singer married a 15-year-old and was accused of being filmed having sex with a 14-year-old.

Yet he has eluded years of allegations by African American girls that he held them as sex slaves. Those are just the celebrity-driven cases.

In just the past few months in suburban Washington, a track coach in La Plata, Md., was accused of abusing 42 kids; a soccer coach in Montgomery Village allegedly targeted a 7-year-old girl; and a third-grade teacher in Rockville was convicted of abusing four children after being given repeated reprimands by his bosses for years.

Teachers. Coaches. Priests. Sergeants. CEOs. Judges. Shift bosses at McDonald’s.

The president.

Or rather: presidents.

All of them were believed, and the women and girls were not.

Remember the outrage when former assistant Penn State football coach Jerry Sandusky’s sexual abuse of boys blew up?

In that case — thanks to a different societal kettle of stupid — the boys were not the ones who spoke up.

In fact, it was a boy’s mother who first reported Sandusky had showered with her son. And, her concerns were ignored.

Once that case blew wide open, the outrage rocked the nation. The newspaper that exposed it, the Harrisburg Patriot-News, won a Pulitzer Prize. The newspaper that broke the Nassar story, the Indianapolis Star, did not. They were not even finalists, despite the fact that their investigation also found at least 368 gymnasts who said they have been abused by coaches over the past 20 years.

Because the abuse of boys somehow, subconsciously, seems more deserving of our outrage and seems more monstrous — a toxic brew of homophobia meets misogyny — than the abuse of girls.

Would you believe half of the 9,000 members of SNAP — the Survivors Network of Those Abused by Priests — are women? Including the group’s founder?

Nope. Most folks do not know that hundreds of those priests’ victims were also girls, not just boys.

Even after hearing from 156 of his own victims, as they reminded Nassar of the smell of the lotion he used to masturbate in front of them, the way he positioned their mothers so they would not see his hands in their vaginas, Nassar still did not want to believe them.

“Hell hath no fury like a woman scorned,” he wrote in his letter to Judge Rosemarie Aquilina, complaining about the unfairness of it all to him. His words made the courtroom of women and their families audibly gasp.

After reading it, Aquilina — the ferocious judge we needed right now — tossed the letter on her desk like the fetid, rotting pile of garbage it was.

Yes. This happened. It was real. The girls were not lying. And, right now, in schools, churches, gyms and workplaces across this country, it is happening to other girls, other women, who still fear what they will face if they come forward.

Stop doubting them America, and stop enabling their abusers.