Let me teach you the most important phrase you can ever know in the subject of apologetics: “Prove it”
That’s right, prove it is the best thing you can say in the face of these things. A website can claim anything it wants, including that X is a satanic symbol used by pagans… but unless they cite an authoritative source to show they aren’t making it up out of thin air… the answer is “prove it” and throw their argument away as the garbage that it is.
And this is the mentality you should bring WHENEVER you hear anti-catholic rantings and ravings: if they can’t back up every assertion they make with evidence and proof, then their assertion remains totally unproven and therefore completely unreliable.