Cruz wasn't being challenged to produce and example of a church being persecuted here. Rather, he chose to bring up the topic. So he plowed ahead with a prepared talking point - a talking point which would "prove" how churches are being persecuted.

So there he was, example in hand .. but what was the example he chose to bring out in the interview?

A Mennonite couple who purchased an old decommissioned Lutheran church building. The Mennonite couple re-purposed the building, and ran it as a small business, specifically as an art gallery.

Because their art gallery looks nice inside, they rented it out for events, including weddings. So they started themselves a little banquet and party-hosting business out of an old building they bought.

But Cruz made it sound like these Mennonites were running a Lutheran church (huh? how does that work?). To Cruz, it seems a building which was decommissioned (desecrated) will still forever be a "church" and anything that is done in that building is now a "religiously protected act."

He purposefully injected Lutheranism and the Mennonite religion into the situation, but this was simply a small business operating in a building which had a little bit of past religious history to it. He spun a tale that muddied the waters in order to convince listeners that a church was being forced to perform gay marriages.

To Cruz, this was THE example of a "church" being forced to perform a gay marriage. When your carefully chosen shining example of an injustice is a bald-faced lie, it shows that your other examples are probably pretty shady, too.

tl;dr: Cruz prepared his "best example" of a church being forced to perform a gay marriage, and it was nothing but a bit of fast talk.