Spain, Portugal, England and France all wanted to establish territories in the Western Hemisphere. The reasons were to gain more territory and to take advantage of all the raw resources found in the New World, Especially gold and silver along with timber and other resources. It was for a Competition of the Empires so that they'd become the most powerful in the world.
Several meanings could be agvined to this. On face value, Dr. King is saying that the men who lynched Emmett Till were morally bankrupt but hid behind Christianity and rationalized their actions for murdering Emmett for allegedly flirting with a married white woman.
