Your argument is a logical falsely. It is not an either or equation. In addition what the hell does going to church have to do with being an evangelical. Most young Christians do not attend the secular churches anymore. look at a Christian concert sometime, most of those Evangelical kids do not go to churches that are embracing gay marriage etc.
The kids who go to Christian concerts are liberal, air-headed Obama supporters more interested in social justice and feel-good, rock-star Jesus than actually living the gospel. I know that from experience—I've tried dating in that crowd, and for hearts supposedly full of love, they certainly seem to be real snow queens! (The ones that aren't, and there are quite a few, usually are married very young.) Modern Christian music sucks, only good for whipping up the same type of mass hysteria you see at Trump rallies.
Nowhere in that article does it say that most of Trump's self declared evangelicals do not attend church regularly. It DID say that 38% of ALL his supporters attend church regularly...it did not break down data within the self-declared evangelicals as you asserted.
No, the article (which drew from a separate poll, I just chose that one because that was the first search result I was able to pull up from this site's archives) said of the Trump-voting evangelicals that 38% said they attended church regularly. Only 38% of supposed "evangelicals" actually are part of a church. They say they're Christians, but they're not actually practicing.
Believe me, I attend church fairly regularly and Donald Trump is treated as a sick joke there, a symptom of how far gone our country has become.