Matthew 7:26 And every one who hears these words of mine and does not do them will be like a foolish man who built his house upon the sand;
There are many people think that this text is about building sand castles. And they believe the point is why spend time building something that won't last. They look at this as something similar to the story of the 3 little pigs, a story about building materials, they think the point is build with something that will last. As good a lesson as that is, that's not the point of this text.
If you want to understand this text, you might look at it as building castles on the sand, that is sound buildings that will not stand because they have no solid foundation. If you think about that, you can see that this is not a wise thing either - even though it should last it won't last long, as soon as one good storm comes, everything will fall.
Many people however live in hope that what they have build will not fall, and when the rain comes, they pray to God to save what they have built. They are usually disappointed because while God loves us, and sent his son to die for us - Jesus didn't die to save our stuff, but to save us from our sins, and to open heaven to us.
The center of the text, and the key to its understanding are these words "every one who hears these words of mine and does them" - the problem is that its really not about what we do, but it is about what God does in and through his Word.
If we are saved because we have heard the Word and done it we are saved by our works, and we know that this is not the case. Jesus is not talking about our salvation here, he is rather talking about our stewardship of life. Because we believe teach and confess, that we are saved by grace through faith, and not of works. The forgiveness of sins and eternal life are a gift of God, hearing the Word and doing it is not our works, it is simply the faith that grasps the promises of God and hold to them. But once we know the way of salvation, what do we do with our life?
That is the center of this text. If you build your life, if you build your treasures, if you build what is important centered in Christ, those things will stand through the storms of life. The church is an example of something that will stand - Jesus promises that not even the gates of hell can prevail against it, but will remain until the end - it may be shaken, for storms can do that, but it will stand, because Christ is its foundation.