Why Judaism and Christianity but not the others?
If we say that Judaism and Christianity are faiths, but others aren’t, then the adherents of other faiths can say the same about Christianity and Judaism - that they aren’t truly “faiths” but what they believe is a “faith.”
“...the adherents of other faiths can say the same...”
I really don’t care too much about what others say. I believe my Christian faith to be valid and I try (and often fail) to live my life that way. That’s all I can do and I have faith that my creator will forgive my short comings.
If some prefer to worship the moon or some multi-headed nightmare or a toadstool that is their choice. They need not worry that I will be coming after them with a sword. I have enough to do keeping myself on the right track.