What many claim as 'idolatry' among Catholics is an erroneous claim. It is simply explained thus. In centuries past, the vast majority of early Christians were illiterate. So there was a very important measure taken by the early Church when constructing their places of worship, that they e.g. incorporate into their stained glass windows, as one will find in Churches and Cathedrals throughout Europe, the depicted story of creation, or the life of Christ, and various aspects of the Gospels, as a medium of instructing the worshpers.

The same applies the people retaining images of their Saints, so that they could be also venerated for their great contribution to spreading of the gospel, their teachings, like St.Francis of Assisi. The images were there to remind the faithful, and also so they would not be forgotten over hundreds of years. Remember people who could not read had only the vernacular to go by and the images of Jesus, of His angels and of His saints.

So, to be correct, Catholios do NOT worship Mary , angels, or saints. We worship ONLY God and His Holy Trinity, period.
We venerate the others. So that is a complete and utter falsehood propagated by the likes of dissenting Martin Luther, or Henry XIII, whose religion was basically founded by his own ego, as he wished to put himself above God's Law, and willfully live an adulterous life.