Student question: “Besides dying, is there a line drawn between honoring a dead saint with images, and worshiping idols? How are they distinguished?”
This is a place where “theological incorrectness” is an important insight: I can tell you what some of the official teachings of various Christian traditions are, but it may vary quite a bit from the diversity of practices that Christians who are identified with those traditions engage in. Many people pray “incorrectly” according to official teaching, but from the vantage point of the academic study of religion… their practice is equally worthy of examination and critical appreciation.
So one account of the official teaching is that prayer to the saints and angels is not idolatry because it recognizes that all of the holiness, goodness, and power of the saints and angels is derivative. That is, it takes its origin in God and never competes for the glory, honor, or love directed to God. While it is true that typically prayers to “dead” saints and martyrs predominate as forms of piety, it is not death that makes prayers to saints different from communication with other persons.
One might ask a living person for a blessing or healing, just as one prays for divine intervention from a “dead” saint: the difference is that typically one does not expect a living person to hear the prayers of your heart without physical proximity and verbal request. Death is not what makes a saint differ from other persons we might ask to pray for us (that’s supposed to be God’s gifts of holiness and divine presence); death is just required prior to official canonization. After all, from the perspective of the pious, the dead saints are not actually dead at all—they are alive as eternal and glorified souls with God.
However, in practice, prayers to saints and angels often look like prayers to demi-gods or minor deities in a hierarchy with the Creator God… this can be true whether the saint is dead or alive! This is why people are accused of treating saints as idols—that is as distributing divine power independently from God or distracting the pious from sole focus on God.