In scene 2 why couldnt macbeth say amen?

Macbeth could not bring himself to say "Amen" in scene 2 because he was already deeply consumed by guilt and remorse over the murder of King Duncan. He felt a profound sense of shame and horror for his actions and was unable to find solace or comfort in the religious ritual. When the devout Thane of Cawdor said, "Amen," Macbeth's inability to echo it revealed the moral crisis he was grappling with. The unspoken word "Amen" represented his inner turmoil, his rejection of divine forgiveness, and his descent into darkness.