“all the other sects, (There is but One Church) have as their founders, sinful men”
Nonsense. There were many congregations founded by the Apostles who, holding the same doctrines from their founding, were suddenly declared heretics because they would not confess new doctrines that had become popular. The Catholic church has a long habit of doing that. It’s quite easy to claim there is universal agreement in the Body on your peculiar doctrines, when you routinely chop off the limbs that don’t agree.
No.
Heresies, yes