1 Corinthians 3:17
“If any man destroy the Temple of God, him will God destroy.” Do you mark the sweeping vehemence of his words? However, so long as the person is unknown, what is spoken is not so invidious, all dividing among themselves the fear of rebuke.
“Him will God destroy,” that is, will cause him to perish. And this is not the word of one denouncing a curse, but of one that prophesies.
“For the Temple of God is holy:” but he that has committed fornication is profane.
Then, in order that he might not seem to spend his earnestness upon that one, in saying, “for the Temple of God is holy,” he adds, “which you are.”
Source: Homilies on First Corinthians (New Advent)