1 Corinthians 3:13

Every man's work shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man's work of what sort it is (KJV)

Then: Did the Corinthians already know this? They knew about the second coming of Christ. They knew that all would be judged on the last day. But they may not have thought about it in this way. One thing for sure, what's ahead is personal for every believer. This will not be a whole group experience. Baker (p. 57) reminds readers about the many ways buildings can be tested - weather conditions, decay through time, or military destructions by fire. Burning was Corinth's experience when Luccius Mummius sacked the city in 146 BC. Corinthians could still see the remains of some of those buildings. Baker also infers (p. 58) that some of the Corinthian leaders were doing good work. Otherwise the metaphor would have reflected complete destruction with nothing left standing.

Now: Matthew Henry understands the passage to apply to all believers, while Baker believes Paul's main concern is with the leaders and teachers. Since it looks like the teaching is universal, not limited, and since Paul speaks through access to the Holy Spirit, no one following Christ can set this aside. It's not an easy thing to anticipate, but, remembering that Paul's purpose is the salvation and eternal life for his hearers, believers should consider it to be a warning.

Extra Source: Cornerstone Biblical Commentary 1 Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.
Commentary on the Whole Bible Acts to Revelation Vol VI by Matthew Henry online at
http://www.ccel.org/ccel/henry/mhc6.iCor.iv.html