I don't think that we can tell 1 B+ people that they're doing it wrong when it comes to their faith.
Yes we can (heh...), since they are doing it wrong.

There are hundreds of millions of Muslims who have no problem living with us in the modern world.
But they don't seem to have any problem living with murderous jihadists laying claim to their faith either.

Yes, yes, you may quibble that some imams here and there are issuing statements condemning each new atrocity as it happens.

But if they really want to differentiate themselves from the murderous jihadists then it's on them themselves to get rid of the murderous jihadists. Namby-pamby condemnations are of no use.