However "Get back to where you belong" could also, and reasonably, be applied to anyone on God's green earth, since "where we belong" is within the will of God; God wills that all men be saved, and come to a knowledge of the Truth; and Christ established His church for a reason, namely to be the "pillar and foundation of the Truth."
So it stacks up to be practically a syllogism. If not quite apodictic, it's at least a reasonable inference that everybody ought to be a member of that Church which He founded, which is the Body of Christ.
I wouldn't expect all the members of the FReeper Brethren Fellowship to snap to attention and say "Oh, I get it, I'm supposed to be a Catholic" --- most people are not, actually, much moved by reasonable inferences --- but this might give you an insight on how a Catholic would see it.