Science

From 'Eugenics and other evils', chapter VII:

The thing that really is trying to tyrannise through government is Science. The thing that really does use the secular arm is Science. And the creed that is really levying tithes and capturing schools, the creed that really is enforced by fine and imprisonment, the creed that really is proclaimed not in sermons but in statutes, and spread not by pilgrims but by policemen - that creed is the great but disputed system of thought which began with Evolution and has ended in Eugenics. Materialism is really our established Church; for the Government will really help it to persecute its heretics. Vaccination, in its hundred years of experiment, has been disputed almost as much as baptism in its approximate two thousand. But is seems quite natural to our politicians to enforce vaccinations; and it would seem to them madness to enforce baptism. 

I am not frightened of the word "persecution" when it is attributed to the churches; nor is it in the least as a term of reproach that I attribute it to the men of science. It is as a term of legal fact. If it means the imposition by the police of a widely disputed theory, incapable of final proof - then our priests are not now persecuting, but our doctors are.

 I have to say that I do not agree with Chesterton completely; I do tend to trust specialists, and I do not necessarily believe the common man with his common sense will have the right view of scientific theories. But it is good to realize that the scientific worldview (even in a specific area) is not as immovable as some popular writers tend to express.