1. Church should be boring. Very little in Scripture indicates that worship and life together should be thrilling. There are not sporting events, concerts, movies, novels, or entertainments in the biblical witness. Promising that church will be exciting sets up a false expectation that is not sustainable long-term, and lacks truthfulness.
2. The church should be in danger. Collectively we tend to work for safety, gather for safety in numbers, and worry when the building isn't locked up, the finances aren't steady, etc. But the church of Jesus Christ is thrown into the world not for safety and security but for the neighbor and their needs.
3. The church should seem sinful not saintly. That most churches appear to be constituted by the upright and moral is a problem, because Christ's church was originally formed of prostitutes, tax collectors, and other sinners. The middle class, bourgeois captivity of the church sends a signal to the poor, downtrodden, and outcast, that the church is not for them except inasmuch as the church benevolently "helps" them.
4. Clergy are the new monastics, and all the skepticism concerning monasticism in the reformation period applies equally to clergy today. The laity "elevate" the priesthood and fail to see their own vocations as holy callings from God. The clergy still enjoy the benefits that come with this "elevation."
5. More worship (and more sermons) should be incomprehensible, mysterious, and downright weird than is currently the case. All our attempts at "rational" worship are vitiating the holiness of worship.
6. Churches should break the law more often. Many current legal structures violate the gospel, and the church has become too co-opted by the culture to even know it is being co-opted.
7. That really is Jesus Christ you are eating in the Eucharist. Don't miss it.
8. That baptized person next to you in worship really is a member of your own body. Literally. For all eternity. Get used to it.
9. The church is an open set, not a club. If the church is living as a church, strangers will come in and change things. And just when the strangers have gotten used to the changes, more strangers will arrive. So church is always estrangement, and that is a good thing.
9.5 God probably doesn't care that much what kind of music you like.
[I violate most if not all of these theses in my life and ministry, but nevertheless believe they are true and theologically faithful.]