Final answer:
Martin Luther King Jr. criticizes white moderates for their lack of action and the church for its failure to take a strong stance against racial injustice.
Step-by-step explanation:
In his 'Letter from Birmingham Jail,' Martin Luther King Jr. criticizes white moderates for their lack of action and their preference for maintaining the status quo instead of actively supporting the civil rights movement. He argues that their desire for order and their fear of tension hinders progress in the fight for justice and equality.
Additionally, King criticizes the church for its failure to take a strong stance against racial injustice. He criticizes white churches for being silent or providing only shallow support, emphasizing that true Christianity should inspire believers to fight for justice and equality.