Who are the barbarians?

I came across this quotation earlier today, while watching a history documentary.

"We cannot command in matters of religion, because no one can be compelled to believe against his will."


Sounds fairly modern and progressive, doesn't it? A product of the Enlightenment, or even more recent than that, perhaps. In fact, it is attributed to a monarch who not only lived 1500 years ago, but whose people are widely considered to be barbarians - Theodoric, king of the Ostragoths (454-526, reigned 471-526). If a 'barbarian' from the so-called Dark Ages could espouse such a belief, why is it seemingly so difficult for so many people in the 21st Century, of many different faiths, to extend that courtesy to those who don't share their worldview?

Love & best wishes to all
Sammy B