"O ye who believe! surely,
the idolaters are unclean (al-mushrikoona najasun). So they shall not approach the Sacred Mosque after this year of theirs. And if you fear poverty, ALLAH will enrich you out of HIS bounty, if HE pleases. Surely, ALLAH is All-Knowing, Wise. Fight those from among the people of the Book, who believe not in ALLAH, nor in the Last Day, nor hold as unlawful what ALLAH and HIS Messenger have declared to be unlawful, nor follow the true religion, until they pay the tax considering it a favour and acknowledge their subjection.
And the Jews say, ‘Ezra is the son of ALLAH,’ and the Christians say, ‘the Messiah is the son of ALLAH;’ that is what they say with their mouths. They only imitate the saying of those who disbelieved (kafaroo) before them. ALLAH's curse be on them! How they are turned away.
They have taken their priest and their monks for lords besides ALLAH. And so have they taken the Messiah, son of Mary. And they were not commanded but to worship the One God. There is no God but HE.
Holy is HE far above what they associate (yushrikoona) with Him! They seek to extinguish the light of ALLAH with their mouths; but ALLAH refuses but to perfect HIS light,
though the disbelievers (al-kafiroona) may resent it. HE it is Who has sent HIS Messenger with guidance and the religion of truth, that HE may make it prevail over every other religion,
even though the idolaters (al-mushrikoona) may resent it. S. 9:28-33 Sher Ali"
So, anyone who worships Christ or Mary is worshipping anyone, but the one God according to your own belief system. That is why there are numerous clerics in their sermons calling Christians polytheists. I told you, I actually listen to sermons and what's being said in other countries. I don't just take articles I find on the internet.
And, Walid Shoebat (who comes from a terrorist family and converted to Christianity) has even explained those accusations and what's being taught in a lot of mosques. So, as per usual, I would like to invite people to look things up.
So, here's the thing. According to your own book. Christians - who venerate, praise, and worship Jesus as well as God. And Catholics - who venerate, praise, and even pray to Mary, the Archangels, and God - are polytheist and do not worship a single god and, instead, are in apostasy by that very verse's phrasing. Hence, by practicing what their religion says and teaches - they are insulting Islam. It's pretty clear how anyone who believes Jesus is the son of God (as per Christian & Catholic belief) is considered a nonbeliever.