Lachlan
Great Builder of Civs !
And Lachlan, The HRE wasn't Holy, Roman, or an Empire (love that quote).
The unification of Christianity into a mainstream european religion was Emperor Constantine of the Romans. The HRE didn't exist until almost a millenia after the death of christ, while the Romans were still around (thus Constantinople). The HRE actually defied Papal authority, feeling that the Kaiser was the true Pope and that the Pope was a usurper. The HRE probably did more to DISRUPT european Christianity then to unify it.
Constantine converts to Christianity on his death bed and the European world as we know it changes, replacing the Jovian gods with JC.
Oh, sorry, i thinked to Frank empire of Charlemagne
