The definition of vanity is doing something in vain. Truth is if you go to church for the wrong reason, then you go to church in vain. Vanity all is vanity. Now the truth is sometimes hard to believe. The truth is the church is supposed to be a place to worship and pray to God, The was never a place according to Christ, to learn about God.
The only thing to be taught in the church is the gospel. But what is the gospel? According to Christ, the gospel is he came to teach us the truth of what God wanted us to know. That is the things we need to do to get done in our lives to fulfill the Lord's Prayer.
The Lord's Prayer ie not just something to say. It is the fundamental prayer for bringing the Kingdom of God here on Earth. The gospel is the way to heaven by doing what Jesus taught. The results we fulfill the Lord's Prayer in your life. Then you can go to church and worship God and glorify him by what he will be doing in your life, which will edify the church.
Then the church will be one here on Earth, Christ will be the High Priest he has always been, and we will recognize him for who he really is. And the church will grow and, people will no longer fear death.