Here, he focuses on what should happen after that foundation of Christ has been laid. Once the foundation is laid, you don’t just stop there; you add more to that. You have to anchor to that foundation, but you keep building and keep learning additional stuff and teachers teach additional doctrine.

I think Paul was making the point that whatever else is taught that builds on the foundation of Christ needs to be good and valuable and lasting so that when the trials come (as they always do) we can endure through it.   

Paul suggests different building materials people might use in their building—gold, silver, precious stones, wood, hay, stubble—and compares that to various types of doctrines that could be taught, then says the fire will try every man’s work. 

We can eyeball each of those materials Paul lists and have an idea of how they would stand up to fire. Gold and silver will still remain, although, depending on how hot the fire gets, they may melt. Precious stones will melt at a very high temperature and pressure, but I don’t know if Paul knew that. Perhaps he considered them most enduring. They certainly wouldn’t be completely burned; they’d just change to a different sort of form that would handle it better.   Now, wood, hay, and stubble would most obviously go up in flames immediately, so they wouldn’t be the best building material to build with if one expects to go through fire.  I suspect Paul meant for gold, silver, and precious stones to represent doctrines that are valuable and lasting.

This is a pretty good analogy for the importance of teaching good, solid doctrine because that will get through the fire and result in a reward instead of loss.   A modern-day way of teaching the same principle is that we want to teach nourishing doctrines of milk and meat, rather than

what is sometimes called “doctrinal twinkies” or “fried froth,” because when a famine of the Word hits the world, the twinkies and fried froth are going to leave us feeling malnourished and empty.

Sooner or later, the principles we’ve learned or taught will be tested by temptation or tribulation or persecution, so if we have to have that foundation of Christ and then solid, edifying doctrines to stand up to it. Otherwise things collapse, and it is really hard to rebuild in the middle of a storm or fire.    I’ve heard stories of people who have had to rebuild their faith in the middle of a tribulation, and my heart goes out to them. It’s possible, but it is very hard.