The term miracle implies a public event or phenomenon caused by something supernatural, like a magical or mythical power. So if you doubt the supernatural, then you are probably sceptical about ACIM.
Nevertheless you may be astonished and impressed by what is extraordinary and inexplicable in the world. Here are a few examples for your consideration. Are they miracles?
1. Are miracles shown by extremely gifted people?
Unbelievably extreme mathematical, musical, artistic, and mechanical abilities have been among the talents demonstrated by a tiny number of individuals. Examples include performing rapid mental calculations of huge sums, playing lengthy compositions from memory after a single hearing, and repairing complex mechanisms without training. They seem something like miracles.
Kim Peek was below average intelligence yet could speed read through a book in about an hour and remember almost everything he had read. Furthermore, according to an article in The Times newspaper, he could accurately recall the contents of at least 12,000 books. Peek enjoyed approaching strangers and if told their date of birth would tell them on which day of the week they were born and what news items were on the front page of major newspapers that day.
Orlando Serrell did not possess any special skills until he was struck by a baseball on the left side of his head in 1979 when he was ten years old. He can recall the weather, as well as (to a varying degree) where he was and what he has done for every day for a period of nearly 40 years since the accident.
Daniel Tammet recited pi correctly from memory to 22,514 digits. It took him five hours and nine minutes. He knows ten languages. He learned conversational Icelandic in a week and then appeared on an interview on Kastljós on RÚV speaking the language.