A building speaks of permanence. So when we build a church building—especially if there is a lot of brick and stone involved—this speaks of permanence as well. But we have to be careful. For Christians, this material world is not the final state of things. However, this does not mean that the final state of things will be ethereal, or spooky, or wispy, or spiritual in any of those senses.
The solidity of a church building speaks of the ultimate solidity of the new creation, when matter will receive its final glorification in the resurrection, and when atoms will be packed together far more densely than they are now. Your salvation, and the salvation of all God’s people, is far more real than anything you have ever experienced.
A church building speaks of this by analogy. A spiritual dullard takes the enacted metaphor literally, and thinks that ultimate reality is found in what we have done, what we have fashioned, what we have made. But the privilege we have in this world is to yearn for the next. The whole creation groans, Paul tells us, longing for the time the sons of God are to be revealed. That groaning creation includes everything we build, including the sanctuary.
The best way to ensure that our building continues to speak the truth about the next world is to make sure it stands against all that is false in this one. The system of the world is wrapped up in the lust of the flesh, the lust of the eyes and the pride of life. Our spire, our sanctuary, our windows, should all be fashioned as an obstacle to those who would find their satisfactions under the sun. In our day, this means that want to build what we build as a testimony against the secular state. We want it to be an eloquent testimony, but that means there will be temptations that come with it—temptations to pretend to be against something we are secretly working for. The answer is, of course, the blood of Jesus, which what this sanctuary must always proclaim. There is no way to preach the gospel and angle for respectability at the same time. So let the stones cry out.