I don't think the priest hated him because he was severely autistic, but he was too disruptive during the mass, and was a physical threat to others as well. His parents probably refused all accommodations, including the thought of having someone bring Communion to their home because they wanted the community that their church provided. I think that the autistic kid could have been uncomfortable because of sensory overload, and his mother didn't notice or care that he was uncomfortable. NT's who are forced to go to church by their parents find other ways to rebel without disrupting the service, but this autistic kid didn't have any other way to communicate. In the end, that priest did that kid a favor because one way to make someone hate organized religion is to force a child to go to church when they don't like it.
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"I do not feel obliged to believe that the same God who has endowed us with sense, reason,
and intellect has intended us to forgo their use."
- Galileo Galilei