A sign in the sky...
Constantine did indeed understand languages from the Roman province of Britannia.
But the "sign in the sky" was not real.
At the moment when Constantine made a "religious revolution", he was engaged in sort of a civil war against his rival Maxentius, they were both trying to become emperor. Each one had his own military forces.
see here:
http://en.wikipedia.org/wiki/Constantine_I
Constantine's religious move was a fantastic propaganda success. Indeed it was a good idea to tell his soldiers that a new God fought with them...
The conditions of Constantine's religious decisions, due to a civil war between two emperor candidates, are slightly opposed to Christian principles, and that does not give Constantine the image of a true Christian, because the Jewish reformer Jesus from Nazareth had preached peace, not war nor a religion at the service of an emperor.
Unfortunately Gutenberg came only 15 centuries later, and Jesus had no opportunity to have his ideas published in a book at lifetime.
Jesus' religious reform was "stolen" by the Romans who found an opportunity of the first fierce antisemitic propaganda since the concilium of Nicea.
Jesus also wanted to have the Roman occupation ended in his country. His greatest enemies were the corrupt priests and Jewish king, collaborators with Rome.
Maybe Jesus can be considered as a "Jewish mixture of Luther and Mandela" who failed due to Roman occupation and repression in his county.
And Jesus was not the first nor the last Jewish reformer, who indeed wanted to reform and direct Judaism away from materialism "back to the roots". But these very religious people were often misunderstood and abused off by their disciples after they were dead.
The next leader came 70 years later, he was not betrayed, but failed in the Roman siege and final Jewish defeat in Masada.
The overnext one came 5 and a half centuries later. Not Jew by birth and not living in the same country, he was inspired by the Jewish Diaspora and wanted to guide the people in his own country to a reformed Judaism. In his lifetime he was rejected by the rabbis. And after his death, he was also betrayed by his own religious successors. These successors did not live for long. For a period of several decennies, they murdered each other for succession.
No Gutenberg, no authentic religious ideas of these people preserved black on white for the future generations.
