Those enormously successful "megachurches" are where all those missing Protestants have gone. The mainstream protestant churches (with 1 or 2 great exceptions) have largely fallen prey to secular humanist ideas. "Be ye holy for I am holy" is the spiritual battle cry.
I wouldn't as an ordinary sinner ever make such an idiotic claim that outside of my church there is no salvation. Yet people that are called into Christ's holy family feel the need to boldly claim that they are members of the "true church" Nothing could be more prideful, divisive,or uninformed. God can't be subject to man's petty puny ideas. He's God after all.
I'm not gonna stoop so low as to denigrate the RCC. That would be a sin.
Agape, DrMike
We do not say there is no salvation outside of the Catholic Church. Like you, that is not our place to say. The Church as well teaches that others may be saved.
Amen Dr. Mike. If only our fellow brothers and sisters in Christ would mark their walk with that level of humility.