"For first of all, when ye come together in the church, I hear that there be divisions among you; and I partly believe it. For there must be also heresies among you, that they which are approved may be made manifest among you." (I Corinthians 11:18-19)
So at a minimum Paul found one church with divisions and heresies, those approved by the congregation manifested among them. It wasn't just what they thought was true, but they acted out the errors.
Before there was such a thing as the internet and discussion groups, it was necessary to visit any church where eventually it would be learned what they believe, and whether their actions show forth false beliefs. One agreed and stayed, or became alarmed and resumed church-hunting.
Now we can select a local church online and go read their statement of faith, at least finding out their professed doctrines. From there it's likely to take personal experience to discern whether they do what they say they believe. But to some degree there's testimonies online that can give a preview of what to expect.
In the whole process, these discussions keenly compare such things so that each person participating can learn what the divisions and heresies are, if any, and eventually for the Holy Spirit to help sort the tares from the wheat at least for each of us individually.
I've observed many times that members of a congregation might have a brochure listing their fundamentals, or a poster in the lobby, accepting them without question without having enough Bible knowledge to question anything about their church. The list is then equated to the 10 Commandments on stone tablets, though most probably couldn't quote those or even find them in the Bible. Even traditions not mentioned in the Bible become part of their doctrines. To them they are not divided, have no heresies. Most will never take a look at what another church believes, as that doesn't matter to them.
The people that are alarmed over divisions and heresies are mostly
us who do look at the various church doctrines online. We are not at peace about it because we're learning how deadly false beliefs and Bible ignorance can be. I've watched hundreds of dedicated online members drop out from weariness dealing with it. Little no no change will come of it from us, except maybe between some of us, but that won't change those churches out there that are in error, especially if "we" don't bother attending a church.