Let's let Jesus address that when he says.....“Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven”........
As for slandering....as I see it the statements opposing catholics are not intended to be malicious or injure individuals...that does not mean what is stated wouldn't do so, especially for those with high sensitivities, or those who might have a sense of conviction when the truth is revealed as so.
What I have seen is generally those who feel slandered are those who are opposing the truth.....especially when they have no argument or are unable to defend their position, if they have one at all...sometimes some simply like to get in the way.
Sorry, but following Self and Self Alone isn't following Christ, the Holy Spirit didn't take a fifteen hundred year long vacation, and thousands of little groups claiming to have the truth don't supersede His Church.
That trash about a deliberate slander being something someone feels because they're opposing the truth may be cute for the Politically Crowd but it's an obvious canard to avoid a straight up yes or no answer.