Protestants have many complaints about the Catholic Church. One of the most frequent I come across is the accusations concerning "idolatry". Although often refuted, they can't seem to let this one go, like a dog with a bone..
So I'd like to unpack this ever-recurring misconception. The Catholic use of icons, whether they be paintings, statues or some other medium, is not the same thing as paganism/idolatry. The proper understanding of idol worship is actually the worship of someone or something other than the One True God. It doesn't even have to involve a physical object, statue etc.
Catholic icons are simply a focal point, something tangible to ray towards (not *too*); and in the case of Mary and the Saints, these prayers are veneraton, not Worship. Worship consists of sacrifice, as in the Holy Mass. No one offers sacrifices to Mary or the Saints, Angels etc.
The technical terms for veneration vs. Worship are " dulia" and "latriea"-- Latriea is the word for Worship proper, and is where we get the suffix "-olatry". The Protestants think Catholics are performing Latriea when it's really " dulia" i.e. venertion.
An illustration is that God forbid your dear mother dies, and you ave her photograph. You look at it every now and then to say "I love you, mom". That would hardly be seen by anybody in their right mind as " idolatry"! Yet this is precisely what Catholics are doing when they pray to Mary & the Saints.