Buildings require solid foundations for them to stand against winds that beat against them. They require solid foundations for them to fulfill the specific purpose of their designer.
The Church is God’s building. Not the church building, but the Church. God’s people, Christians are God’s building. And God is building us up more and more in the image and maturity of His Son, Jesus Christ. And we will not be built up well as Christians or fulfill the eternal purposes that God has for us without first laying a very solid foundation.