If you read the article, it's actually a fairly nuanced look at how a "Christian Nation" means very different things to different people. Most people who say they want it have relatively benign thoughts about what it means.
I'm just saying that the article doesn't say nearly half of Americans want a theocracy.
60-80% of Americans still identify as Christian from a quick google search. The percentages are lower in young generations, but still very much in the range that this is a plausible number.