We see much evidence from the NT that ‘all believers’ are to be of one heart and one mind. They are to agree. That is very different than what we see in Christianity today.
We can also refute the claim that ‘the church’ is invisible and includes all believers, because the church that Jesus founded must be a visible, authoritative church. If we disagree regarding faith and morals we need to be able to go to an authority to find out what is truth. How can we find that authority if the church is invisible?
The bible itself is authoritative, but then we get into two different people reading the same text and understanding it in different ways. Again, we need to go to the visible, authoritative church to know if either, or both, interpretations are (in)correct.
Cheers!
michel