The Good Morning Britain host claimed the event, which this year had a religious theme, was "disrespectful" and wouldn't dare target different faiths.
Writing in his column on the Mail Online, he said: "Christianity, it would seem, is fair game for a mocking fashion parade."
Stars from the world of music and movies turned out in the event in New York dressed in costumes inspired by Catholicism.
Titled 'Heavenly Bodies: Fashion and the Catholic Imagination', guests were seen dressed as nuns and popes.
Declaring his outrage, Morgan, who identifies as Catholic, said: "I know many people don't believe in any God or religion, let alone Catholicism, and I respect that.
"All I ask in return is for my beliefs not to be rudely disrespected.
"Just as I always respect other religions even if I don't believe in what they represent.
"To me, this year's Met Gala crossed a line and was openly, brazenly disrespectful.
It's reported the Vatican gave permission for the theme and also provided clothes for an exhibition at the event.
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