Well to be more accurate, you might point out that the growth of “Catholics” in California is largely fueled by the illegal Hispanic influx; people who are more likely to vote for the political party enabling their criminality, than because of any religious beliefs.
Similarly nationwide, Catholicism when viewed with raw statistical data suffers more than any other religion from inertia. That is, there are unfortunately huge numbers of people who were born (though not even necessarily raised) Catholic, who when forced to identify a religion on a survey, or some other statistical metric, still select Catholicism. They are no more Catholic than you.
The Catholic vote is a democrat vote and always has been, they only went republican five times in our history and not by large margins, and only once against a democrat incumbent.
The democrats have only won the Protestant vote 3 times, 1932, 1936, and 1964.