(CNN) Paul Rimmer intended to celebrate the end of Father's Day at church with his two young sons in tow. But their time together was cut short for what the church considered a disruption and Rimmer considered "rejection."

The family was to attend Sunday's Evensong, a mostly sung-through evening service, at King's College Chapel in Cambridge, England.

The event was particularly thrilling for Rimmer's 9-year-old son, Tristan, who loves the 16th-century church's ceilings and famed Latin chorales. And because he has autism and is nonverbal , he expresses his excitement primarily through laughter and calls, his dad explained.

But before the end of the service, an usher asked Tristan and his family to leave on the grounds that he was disrupting fellow parishioners, Rimmer said.

In a biting letter addressed to the college's dean, the Rev. Dr. Stephen Cherry, Rimmer frames his grievances as a faux-apology for "lessening the satisfaction" of tourists who visit the chapel and who found his son's form of worship offensive.

On Monday, he published the letter on Facebook , where it's been shared nearly 6,000 times.

"My son might not be able to talk, but he knows perfectly well what is going on around him," he wrote. "He isn't even ten years old and he knows that he is unwelcome."

Rimmer, who teaches astrophysics at the University of Cambridge, said the incident wasn't the first time his family had been asked to leave a church but marked the only occasion a member of the clergy asked for their removal.

"Might I suggest that you place a sign at the front of the chapel, clearly identifying which categories of people are welcome and which are not?" he wrote.

Cherry issued an apology on his blog the same day Rimmer shared the letter. The chapel dean said he "failed [Rimmer] and Tristan" at the service but denied that he personally called for the family's removal.

"Nonetheless as Dean I do take responsibility for the whole life of the Chapel and in that regard I express my unreserved apology and intention that we will do better in the future."

Paul Rimmer said his son, who has autism, was asked to leave King's College Chapel in Cambridge during a Father's Day service.

In an update, Rimmer said he was "touched" by the several dozen churches that invited his son to attend and worship the way he wanted as well as the countless parents of children with autism who offered their support.

The dean met with Rimmer, who said they had a positive conversation about how to make the chapel accessible to all its parishioners.

Public and private institutions like churches and schools aren't always sensory friendly for children and adults with autism. A 2018 study found that children with autism were nearly twice as likely to never attend religious services compared to children without the diagnosis, largely because they or their families felt unwelcome in places of worship.

The diocese of Ely that includes King's College Chapel hasn't shared efforts its made in making its churches autism-friendly, but the Church of England allows the deaf and people with disabilities to serve as ministers

Rimmer and Cherry didn't immediately respond to requests for comment.