ABOUT ten years after the Edict of Toleration, Constantine the Great
adopted Christianity. This momentous decision inaugurated

[52] a millennium in which reason was enchained, thought was enslaved,
and knowledge made no progress.

During the two centuries in which they had been a forbidden sect the
Christians had claimed toleration on the ground that religious belief is
voluntary and not a thing which can be enforced. When their faith became
the predominant creed and had the power of the State behind it, they
abandoned this view. They embarked on the hopeful enterprise of bringing
about a complete uniformity in men’s opinions on the mysteries of the
universe, and began a more or less definite policy of coercing thought.
This policy was adopted by Emperors and Governments partly on political
grounds; religious divisions, bitter as they were, seemed dangerous to
the unity of the State. But the fundamental principle lay in the
doctrine that salvation is to be found exclusively in the Christian
Church. The profound conviction that those who did not believe in its
doctrines would be damned eternally, and that God punishes theological
error as if it were the most heinous of crimes, led naturally to
persecution. It was a duty to impose on men the only true doctrine,
seeing that their own eternal interests were at stake, and to hinder
errors from spreading. Heretics were more

[53] than ordinary criminals and the pains that man could inflict on
them were as nothing to the tortures awaiting them in hell. To rid the
earth of men who, however virtuous, were, through their religious
errors, enemies of the Almighty, was a plain duty. Their virtues were no
excuse. We must remember that, according to the humane doctrine of the