Final answer:
In Martin Luther King Jr.'s "Letter from Birmingham Jail," he criticizes white clergymen who are not actively supporting the civil rights movement.
Step-by-step explanation:
In Martin Luther King Jr.'s "Letter from Birmingham Jail," he criticizes white clergymen who are not actively supporting the civil rights movement. He accuses them of hiding behind "the anesthetizing security of stained-glass windows." This phrase symbolizes the comfort and insulation that these clergymen enjoy within their churches, where they do not have to confront and address the racial injustice happening outside.