How about the Catholic Church?
Doubt it, but your slur is noted. Proably they are getting mixed up about the Trinity. Catholics are usually accused by the bornagains of worshipping Mary, not Joseph as well (unless this is a new one).
Not sure how that would enter into it, since Catholics don't believe in three gods, but say (every Sunday, quite clearly) "I believe in one God [cue rest of Nicene creed]"
The "Christians worship Father, Mother, Son, three gods" stuff comes straight from the Koran. It's not clear that Mohammed ever met a real Christian, Catholic or otherwise.
(The only Christians he might possibly have met were Nestorians, who had been out of communion with Rome for 300 years or so, but it's not clear that he ever met any of them, either.)
In other words, they "got that idea" from Mohammed's fertile imagination based on mangled hearsay about Christian beliefs, probably received third- or fourth- hand.