Okay, prepare yourself for my opinion. Typically, I can’t stand it when people constantly share their opinions on everything. And now I’m gonna be that person for a few minutes.
Here’s the thing: I’m not a fan of non-denominational churches. In fact, they can be outright dangerous. The premise of non-denominational church is that believers will be free from the restrictions of a denomination and from the hierarchy of leaders telling them what to do. Here are my objections:
1) Members of non-denom churches do not know specifically what their dogma is. They don’t know what beliefs connect them to the other members of the church. While the members may all believe in Christ as their Savior, other areas of theology never get discussed. What is your church’s belief about how to read an interpret the Bible? About how to raise children? About sacraments? About why people suffer? About prayer? If a person cannot answer these questions, a red flag should go up.
2) Non-denom churches may not be connected to the larger historical church. Churches must agree with the doctrines of the Nicene Creed, which set out the beliefs for Christianity in the 300s. While many evangelical Protestant churches don’t recite this creed in church, often they will have a statement of agreement with it in their manuals, or their doctrine will align with the elements of the creed. (That is not to say that in lesser matters all denominations will agree; they will not, but the should at least agree on the important matters outlined in the Creed.)
3) Non-denom churches do not have accountability. If a church is not collected to a larger governing body, what happens if a pastor or church member does something wrong? Who will hold that person accountable? Who will serve as a mentor and guide for the pastor? No one.
4) Non-denom churches encourage a consumer spirit in believers. Instead of sticking with a church that may be going through difficulties, often people “church shop” for a church that is “more comfortable.” This is not to say that there is NEVER a reason to leave a church. However, that consumer spirit is a product of the American capitalist economy, not of any spiritual truth.
5) Non-denom churches encourage a self-centered user-friendliness. Again, these churches often offer a laid back environment, encouraging members to wear jeans and having a worship style similar to a rock concert. The idea is to make it look and feel more like the everyday world, which will make it easy for people to come and attend services. Personal comfort is a high priority. My argument is if the church looks just like the world, it ceases to be the church. The church is not a place for ME to feel comfortable; it is a place for GOD to be worshiped. It is not about if I get fed or if I like the music or if I get to wear jeans. The question is does the church teach me how to rightly worship God?
Okay, I think I’ll step off my soapbox now. I am interested in responses as I have several friends who attend non-denominational churches. Give me a good argument in return. 
Preach. It. Seriously, I could have written this post. I agree 100%.
I am curious why the interest in non-denominational churches? I do not attend one and quite honestly do not know much about them at all but I would have to say that calling them DANGEROUS seems a bit much. I am sure they can be, however so can many denominations. My take on them is that they are the ‘answer’ for many people to bad experiences within denominations…some of them due to the very things you talked about above – pastors messing up with no accountability or people who were made to feel not welcome b/c they were too much like “the world” etc. I do agree that it is important to know what you believe and good to have a cloud of witnesses surrounding you. BUT I would say the fact that we have SO many denominations would point to the fact that we have not actually ‘figured it out’ and everyone IS in fact choosing where they feel most comfortable and things fit them the best. Non-Denominational is really just another one of those choices. Personally I find it a less than desirable choice b/c as you pointed out there is not much to back it up or to help along the way, however I would prefer it to someone feeling they do not find a welcome in any church at all. Sometimes our denominations can be quite dangerous…
Okay I re-read this and it sounds quite defensive which is not really my intent…sorry if it came across that way. I just know people who at have at least found a place to begin a walk toward God in these churches AND I know MANY people who have been led away from Him due to denominational crap so…I don’t see it in black and white terms.
I am working on my M.A. thesis on this subject. You have listed two ideas that are right on target, the other two are absence of meaningful community=Mega Churches invade areas that are not part of the community around them. The other is non-behavioral religion as in no sense of form because there are no rules. Baptism, optional-not demanded and no record kept. Communion-never regular, objects of communion can be literally everything from matzos to leavened bread, cookies, grape juice in place of wine mixed with water, etc. The holy nature of it is reduced to just a trivial matter, yet the covenant that Christ established is central to our faith. One other fact, most are owned only by the Pastor and he owns everything, including the money you give on Sunday. Whatever he wishes to do, is done because it is a church of a personality, without any formal training and no seminary experience. By the way , have you ever thought through the idea that the consistent claim of spirit inspired faith is no different than the criticism of the Papal infallibility?