On Twitter: Perhaps the question "should Christians be Christians?" is like the question "should Communists be Communists?".
For in its essence, the problem—the poisoned chalice—that Flavius Valerius Aurelius Constantinus Augustus handed the Christian bishops of his day in the fourth century C.E. was closely analogous to the problem that Lenin's successful coup 100 years less two days ago handed him and his comrades.
If you are in a Christian movement, you preach of and model behavior for Kingdom Come, and you wait for God to bring the kingdom of the Heavens.
If you are in a Russian Communist movement, you preach and agitate for the Kingdom, and wait for History to bring the Kingdom of the Earth.
If you are a Christian and Kingdom has Come, you live in the New Jerusalem, and all (at least all the Elect sheep) are happy.
If you are a Russian Communist and the global revolution has come, you receive ample aid from your similarly-victorious German socialist comrades to help you peacefully and productively make Russia a prosperous industrial communist utopia.
But what if you are Lenin and the world revolution does not come? You have "socialism", but only in one country manifestly unfitted for it. You now rule—brutally, because you do not have the social base of a dominant mass industrial proletariat—a poor benighted country? What do you do? The necessities of holding a society of poverty-stricken East African Plains Apes together means that your on-the-ground societal-organization practice must contradict your theory. And so you wind up taking aspect of capitalism that Marx preached against and using them as your business model—and then doing even worse.
But what if you are a bishop in the fourth century C.E. and the Emperor Flavius Valerius Aurelius Constantinus Augustus has given you (a share of) the keys, but not to the kingdom of the Heavens—only to the treasures of the earth. You now have some manner of control, but no New Jerusalem has descended. What do you do? The necessities of holding a society of sinful and greedy East African Plains Apes together means that your on-the-ground societal-organization practice violates your theory. And so you wind up taking aspect that Jesus preached against and using them as your business model—and then doing even worse...