Paul informs the congregation that he can't address them as
He then starts with a building metaphor, saying each person helps build the structure, and at the judgement day, god will figure out how much they've contributed by huffing and puffing and blowing the house down. If it's still standing, like the third little pig's, the wolf won't eat you.
A couple of rules: if you deface the temple, John Cleese will come along and torture you into proper conjugation of your Latin verbs. Also, in order to be truly wise, you'll need to become a fool, because god is ever so much smarter than you. Finally, no glorying in human intellect or achievement.
Paul instructs the congregation to view Apollos and him as explainers of god's mysteries. He admits that a preacher must be trustworthy, but says none of them are qualified to do it, which is mighty convenient. No, only god knows whether he's a good guy or not. He asks them again to stop fighting over who their true spiritual leader ought to be, and to stop acting like they're already in heaven. As for Paul and Apollos, well, they're naked, hungry, starving, homeless, cursed and persecuted which must have made them very convincing. Certainly it has the effect of convincing them.
He's saying all this not to shame them, but to warn them that though they may have many instructors, they have only a couple of fathers, and he urges them to follow him. He says he's sending Timothy to them, but promises to try to get god to send him personally so he can find out who's behind the rumours and whether they're really holy. He then asks shall I come unto you with a rod, or in love, and in the spirit of meekness? (v. 21) A rod, man, always a rod.