J.S. Mill wrote:
"It is a bitter thought, how different a thing the Christianity of the world might have been, if the Christian faith had been adopted as the religion of the empire under the auspices of Marcus Aurelius instead of those of Constantine. But it would be equally unjust to him and false to truth, to deny, that no one plea which can be urged for punishing anti-Christian teaching, was wanting to Marcus Aurelius for punishing, as he did, the propagation of Christianity."
Please help me to understand what Mill means with the blue sentence.
Thank you.
Cadzao