Denouncing Religious Zionists and Modern Orthodox

According to Frumteens, it is a very big crime to refuse to denounce Religious Zionists and the Modern Orthodox as kofrim. It’s worse than refusing to denounce someone that you know to be a child molester:

It is a very big crime, according to the Torah, to be unwilling to call Kofrim "Kofrim".
…As careful as you have to be before you accuse someone of Apikorsus, you have to equally, and even more careful, not to think that what is Apikorsus is not.
An Apikores is like a child molestor in that regard. Before you accuse someone of being one you better know what youre talking about. But if you know someone is one, and you tell people he's not, thats even worse.