I’m not sure if I understand your question.
We have a megachurch in our city, planted by the Willow Creek Association. Approximately 10,000 people attend every weekend (Sat and Sun worship “experiences”). That’s 10,000 people IN ATTENDANCE, not just listed on a membership roster. A few months ago, the church bought another piece of property (an old restaurant) to use for the overflow Sunday crowds. (The sermons and music are all broadcast to the congregation in attendance via video.)
This megachurch has taken thousands of people, including several pastors, from various churches in our community, but it also attracts people who have never been church-goers. That’s a good thing, IMO.
The Bible says that we’ll know they are Christians by whether they obey Christ. This megachurch has put many of the other churches to shame with their active involvement in the community and by leading the community relief for Katrina victims. Many people visit that church because they are curious to know why these people are so GOOD!
In answer to your question, it is definitely a Christian church, teaching Jesus Christ crucified, risen, and coming again. There is no heresy taught, except for the Protestant errors (heresies, if you prefer). But they don’t deny the Virgin Birth, or the literal resurrection of Jesus, or the non-existence of hell, like some of the liberal denominations teach.
It is what I and others call “Christian Lite.” A very simplistic version of the Gospel, basically stating “Believe in the Lord Jesus Christ and you will be saved.” There is no fallacy in this verse of Scripture, is there? Yes, it leaves a lot out. But it’s the True Gospel of Jesus.
I believe, as do others, that the nondenominational megachurches are a “starting place” for someone to meet Jesus and learn basic Christian theology. Once they grow up a little (in the Lord), I believe that many of them will make the switch to deeper churches, including the Catholic Church. We have already had several “refugees” from the megachurch come to our parish, claiming that “they want a deeper theology, more “meat” of the Bible, not just the milk.”
Another function of megachurches and non-denoms is that they are a good place for people who have been hurt in their church or by so-called “Christians” to “hide” for a while and just sit back and rest and recover from the hurt. Once their wounds are healed, they can venture forth and re-join a deeper church that demands more of them. It’s certainly better that these hurt ones attend a megachurch rather than abandon church entirely or worse, curse all churches.
So it’s my opinion that we shouldn’t knock non-denominational churches and megachurches, but accept them as Christian fellowships and remember the words of Our Lord: “If they’re not against us, they’re for us.”