Not true. Not AT ALL true.
Groups of humans take on a collective mindset (think mob behavior) and, as such, can definitely sin.
We all know how a mob can sin. Mob behavior is usually, if not always, a function of the lowest common denominator of the morality of the humans in its group.
So, given that, what about when a church adopts and teaches a heretical, even evil, doctrine (like homosexuality isn't a sin)?
Churches can doom vast numbers of congregants to hell by misleading them. Rarely do individuals have that power.
I make my own personal decision whether or not to join a mob.