I think it was a road paved with good intentions. Also, I'm sure the periodic persecutions influenced a desire to "mainstream" the faith. The problem is no matter the good intentions the result is a step away from the Christianity that Jesus Christ our Lord and Savior gave us.
To get the common people on their side (and their ONLY interest was in "tribute" or taxes, to incorporate them and their nations into the beast that was (is) Rome, they practiced syncretism, worship your idols, only, call them by our gods' names, so therefore Venus is Mary, Zeus is God, etc.
Hmmm. They say leftism and “compassionate conservatism” are good intentions, though I have no doubt that those fostering them know this isn’t true.
No Christian would have agreed with that unholy marriage no matter what the cost or the imagined benefit. It had to have been performed by non-Christians i.e. sons of Satan.
Also, now that those times have passed, why is the edifice still around? If it were Christian, it would have immediately disbanded itself.