We want to stand upon our own feet and look fair and square at the world — its good facts, its bad facts, its beauties, and its ugliness; see the world as it is and be not afraid of it. Conquer the world by intelligence and not merely by being slavishly subdued by the terror that comes from it.
This is what would today be called a “shout out”. It is a rhetorical appeal to the hubris of his listeners–declaring that embracing atheism is a badge of intellectual, moral, and emotional strength.
And this is why the idea will never spread beyond those who live comfortable lives.
Christianity is not a message for the elite, for those who consider themselves as essentially good and in control of their lives. It is a message for those who have suffered enough to know that human frailties aren’t simply going to go away when we commit ourselves to science and make some inspirational speeches. A savior, after all, is of no use to those who think themselves too good to need saving.
No one, perhaps, saw this more clearly than Nietzsche, who called Christianity “a slave revolt in morality”. He hated Christ’s regard for the weak and impoverished, and felt the strong should take control to run the world correctly. But even the spoiled child from a safe neighborhood can grab for control and refuse to believe that his elders have any wisdom to give.
But Christ, when confronted with revolutionaries who were ready to overthrow Roman power (or die trying), simply spoke until they were too weak from hunger to make the trip home. He brought them to see their own weakness before offering them salvation in the form of bread.
And this, I think, is the real value of science to Russell and his intended listeners. It gives them physical bread, which makes them feel strong enough to avoid this lesson of Christ’s.