Per History vs Hollywood: http://www.historyvshollywood.com/reelfaces/breakthrough/

1) Joyce and the pastor never got into an argument. The real Pastor Jason Noble admitted that this scene is fictional.

2) Doctor Garrett (Dennis Haysbert) was white, not black.

3) John's rescuer, Tommy Shine, did not really hear a voice when he was in the water, telling him to keep searching. He had a feeling, as though someone were next to him guiding him closer to the ice shelf.

4) Tommy Shine (Mike Colter) is white, not black. He was portrayed as being an agnostic, but that was not in the book, and he has not confirmed that.

5) Most of the rest was true, including the doctors' belief that a miracle had occurred. See: http://www.historyvshollywood.com/reelfaces/breakthrough/

Tommy Shine (Mike Colter) is now convinced that it was a miracle: ““When you don’t have the answers and you read what the doctor wrote (it was written in the medical record: ‘Patient dead, mother prayed, patient came back to life.) then what is it?” Shine said. “God can’t answer all prayers but we are blessed the outcome worked out the way it did. It’s a pretty amazing story. It was an unbelievable thing. I have no other explanation other than a miracle. His survivability was at one-percent if best.” https://mycnews.com/local-heroes-become-movie-marvels/

Note that the director is Roxann Dawson, who played B'Elanna Torres on the television series Star Trek: Voyager. She's primarily worked as a director since.