A little further down the article goes into more detail about his turn around.
They bumped heads and argued, their relationship strained. In desperation, he turned to God, poring through the Bible, questioning teachings that he once took at face value that being transgender was an abomination. He prayed on it, too, replaying her childhood in his mind, seeing feminine qualities now that he had missed.
Then it hit him. “She’s a girl.”
“I got peace from God. Like, ‘This is how your daughter was born. I don’t make mistakes as God. So she was made this way. There’s a reason for it.’”
Regardless of how he got there, I am glad he did. His daughter’s words say it best.
“There was this electricity in me that was just, it felt like pure joy. Just seeing someone I thought would never support me, just being one of my biggest supporters,”