1 Corinthians 3:1

And I, brethren, could not speak unto you as unto spiritual, but as unto carnal, even as unto babes in Christ (KJV)

Then: Quick switch right here. Paul's next two verses aren't theoretical, but practical and realistic. He hits the situation of the Corinthians with a smack. They must have been shocked. Here he had been dazzling them with an enlightening explanation. Now they had to think about themselves - as carnal, unspiritual no less. Wright observes that the language refers to determined choices in spite of their knowledge of Christ. Thistleton (p. 286) notes that Paul holds out hope for the future with his phrase "not yet" in verse 3:2.

Now: And thus begins the Paul's presentation of "baby" Christians. Church leaders cannot "talk around" the root of a problem if any change will be made in the believers. The issue is not bluntness as much as it is speaking plainly, but rarely do today's ministers address an entire congregation about its shortcomings.
Extra source - The First Epistle to the Corinthians: a commentary on the Greek text by Anthony C. Thiselton (Eerdman, 2000) http://books.google.com/books?id=IHG_DNLpmroC&dq=First+Corinthians+online+commentaries&printsec=frontcover&source=in&hl=en&ei=oCDBSpeoKZ_e8Ab-zKzBAQ&sa=X&oi=book_result&ct=result&resnum=12#v=onepage&q=&f=false