Yes, Christians should never mention “the body of Christ” in church. Especially high profile Christians. They should just sit there and shut up. And put money on the communion tray.
Cruz wasn't in church when he said this. He was at a campaign rally.
From Drudge: At a stop Saturday at Darrell's Place in Hamlin, Iowa, Cruz urged his supporters to "awaken the body of Christ that we may pull back from the abyss."
It wouldn't have been out of place and seen to be pandering if he'd actually been in a church.