For we are God’s fellow workers; you are God’s field, God’s building. According to the grace of God which was given to me, like a wise master builder I laid a foundation, and another is building on it. But each man must be careful how he builds on it. For no man can lay a foundation other than the one which is laid, which is Jesus Christ.
-1 Corinthians 3:9-11
The foundation is Christ. He is the One that all Christians base their faith on. His life, teachings, commands, example, death, burial, and resurrection should be the measuring stick. These facts are the things teachers attempt to pass on to students, the older to the younger, the mature to the immature, and preachers to congregations.
A foundation is only the beginning. It must be built upon to be useful to people. The Christian faith is the same. This building process belongs to each individual Christian. It is their responsibility to construct the strongest, most productive temple for God they can.
Now if any man builds on the foundation with gold, silver, precious, would, hay, straw, each man’s work will become evident; for the day will show it because it is to be revealed with fire, and the fire itself will test the quality of each man’s work. If any man’s work which he has built on it remains, he will receive a reward. -1 Corinthians 3:12-14
People will use different “materials” to build on their foundation of Christ. Paul, of course, is merely using physical building tools to discuss the need to build on their faith with the best quality materials available. These mentioned materials are different qualities, able to withstand different levels of resistance. In the same way, the sermons we listen to, the people we spend time with, our study habits and resources, the service we render, et cetera will have a profound impact on the architecture of our faith. By using the better quality “materials” to build, we will be better able to withstand the challenges, struggles and temptations Satan sends our way.
Do not put the cart before the proverbial horse though. The foundation must be strong. Otherwise just as a building with a faulty foundation is dangerous, a faith built on a faulty foundation is eternally dangerous.
Therefore everyone who hears these words of Mine and acts on them, may be compared to a wise man who built his house on the rock. And the rain fell, and the floods came, and the winds blew and slammed against that house; and yet it did not fall, for it had been founded on the rock. Everyone who hears these words of Mine and does not act on them, will be like a foolish man who built his house on the sand. The rain fell, and the floods came, and the winds blew and slammed against that house; and it fell—and great was its fall. -Matthew 7:24-27
Building a sturdy, lasting foundation requires hearing Jesus’ words and doing them. Without hearing them, we cannot do them. Without doing them, all the furnishing we attempt to do will be for naught.