The mainline denominations in North America are in systemic decline. Why? J.C. Ryle, long dead Bishop of Liverpool has some thoughts on the matter that might be worth investigating. ”Christianity” he says, “without distinct doctrine is a powerless thing.” I think it is powerless for two reasons. First and foremost, I do not believe the Holy Spirit will be present in power to assist the proclamation of the Gospel when it is not the Gospel that is presented to us in Scripture and handed down for centuries in the church. Second, from a purely practical perspective, when the borders of an organization are not clearly drawn people have a very difficult time discerning what the organization is, why they should join it, or even if they have already joined it! The mushier doctrine becomes in a denomination the more rapidly it will decline. God will not bless it, nor will people take the time to investigate it.
The majority of the considerations in the world are already accomplished by people who have maintained trying when there was no hope at all.
Once you get along the side of almost all, it is time to pause and reflect.