Assuming you’re not joking, I’ll try to answer this seriously.
A G rated movie is deemed appropriate for everyone - 2 year olds, 5 year olds, 75 year olds. It’s supposed to be the movie you can take your kid and your grandma to and not have to answer awkward questions during. While I haven’t seen this movie, and it appears that there are topics like pregnancy which are discussed in a “mature” way, making a PG rating appropriate, let’s examine your question at face value.
Would you like to explain to a 4 year old the story of Tamar, which includes lots of sex, rape and prostitution? How about David and Bathsheba? A nice little family tale of adultery, torture, murder - oh, and God kills the baby at the end. Sorry, should I have spoilered that? How about the story of Lot, who tries to throw his own (virgin) daughters to a mob to be raped? Or there was that one guy who committed no crimes, ever, but was beaten bloody by some soldiers, nailed to a stick and died in agony.
There are hundreds of perfectly Biblical, Christian stories that could be inappropriate for children. I hope you didn’t take your kids to The Passion of the Christ.