In a study, a group of theology students were told to preach the story of the good Samaritan, then walk to another building where they'd be filmed. Along the way, they encountered a man in visible distress.
When given ample time, almost all helped. When they were deliberately let out late, only 63% helped. When encouraged to go as fast as possible, 90% ignored the man.
Source: Muel Kaptein