Satan likes them. Their theology originated with Satan. Satan likes to get the Christian busy, busy, busy and not producing.
2/3 to 80% of the chruches in America are pleateaued or dying.
No comment on Satan's activity. I'm not among the privileged few that seem to know his business. Apart from the fact that "he prowls as a roaring lion, seeking who he can devour..." and that he is the "father of lies..." and the "accuser of the brethren..." I'm not privy to what else he is doing in any local context. Perhaps some who are closer to him than I can fill me in...
I know that you blame this decline on a lack of discipleship, but I will suggest that virtually every one of these churches has some form of discipleship program. In fact, I'd lay odds that they are SO busy doing their discipleship program that they don't have time to BE the people of God. I've been blessed to do some church consulting as a part of my work with some seminary professors who do this sort of thing. I've seen other problems that cause plateaued and declining churches beside the lack of discipleship. In fact, the primary reason I see so many churches plateaued and declining is that they are:
1) Culturally irrelevant and in many or most cases just downright weird people. They dress weird, they talk weird, their music is weird, and no one is welcome in their congregations unless they do likewise. I've seen people in these sick churches outright fight to continue their plink-and-plunk hymnbook singing, then the same people get into their cars and rock out or play Country music. I often wonder who wrote the rule that deacons have to wear green suits with plaid pants. Who said that they should decry almost any public activity "sinful" then go out the back door of the church and smoke like chimneys. They have lost their winsomeness to the world around them, not that the church has to imitate the world -- God forbid -- but they also don't have to go out of their way to be 1960s throwbacks... Who ARE those people?
2) Theologically inept and in many cases downright heretical. Many churches make it a matter of pride to be "conservative" but they seriously misunderstand what that means --- they are all about culture and they think they're all about God's Word -- but for the most part they are just proof-texting each other with biblical platitudes instead of seriously exegeting the Scriptures for the edification and building up of the body for ministry. The same ones who are against almost every cultural indication that they actually live in 2011 are downright liberal in their theology. They have, in many cases, become SO human-centered that if God actually showed up, no one would even recognize Him.
3) Many of these failing churches also have failing or failed leadership. Though I recognize and support the congregational model where each church is autonomous and "calls" their own pastoral staff, what I see in practice leads me to believe that most churches do not actually get the right leaders, and even if they do somehow arrive at the right man, they fail to allow him to truly lead as the professional pastor he is. In fact, rebellion against the pastor is one of the key issues that drives down membership and growth.
4) Many of these failing churches also have no real idea about their purpose, and their identity in the gospel. The main purpose that I've discerned in most of the churches I've worked with is to "meet again next Sunday (Wednesday, etc.)" They have no sense of mission, no work to do, apart from satisfying their own demands, wants, and wishes, and they've in essence learned one of the most disastrous of all lessons, that they can vote themselves comfortable, and this is not a strike against making the building modern and adequate -- far from it -- rather this is about them directing their time, talents, and resources to stuff that is neither essential nor missional, nor particularly godly. We know, from multiple accredited national surveys that a very high percentage of those who come to know the Lord do so before age 18, yet the youth and children's ministry is almost an afterthought in many dying churches. That is weird... They let any idiot who is silly enough deal with the youth and God help them if they make noise or some mess somewhere. Don't even THINK about asking for some money... These are leadership and rebellion issues. They also fail to know their biblical identities as Christians -- learners, ministers, missionaries, family, and worshipers. They may do one of these areas to the exclusion of the others, and in so doing, miss the boat scripturally.
I am currently pastoring a church that has doubled in the last four months that was shackled by some troublemakers. When I came, I started teaching them how to make disciples by doing personal discipleship.Every man I currently meet with meets with at least one other man.
Personal discipleship quickly silences the bulldogs who think they know what reaches people but are not personally reaching anyone. The bulldogs are surrounded by those who are reaching people. At this point there are those who are asking about removing the troublemakers in leadership who are not reaching anyone. The proof of leadership is in reaching people and leading them.
To the above, I would say, kudos... Doubled from what to what, though? The church I attend has built a congregation of 2200 in 10 years by operating within the whole counsel of the gospel, including community, and the biblical identities I mentioned above. We're doubling in size every 3 years at the current rate of growth.