Idolatry in the Early Church

At what point does marian devotion or veneration turn into idolatry? A man commits idolatry when he honors and reveres a creature in place of god. In the early church, there was a heretical sect called the coleridians. And they talks about how they offered cakes on altars to mary. But the only thing we should offer on an altar is the body and blood of jesus christ. We should only offer that to the father in the holy sacrifice of the mass. Offering sacrifices to mary would be idolatry. So i think catholics have away to honor mary as the mother of god without divinizing her.