Yes, and that’s why I know what you posted didn’t make sense.
Let’s examine it shall we? Let’s take out the parenthetical phrases:
“The existence of the Catholic Bishop of Rome Sylvester I who approved Constantine the Great’s 321 AD Edict - changing the Sabbath to Sunday.”
It still doesn’t make sense. Is the sentence about the existence of Sylvester? Is it about Sylvester’s action? And if it is about Sylvester’s action should there be a point to the action at the end of the sentence? Here, look at this version:
“It was Pope Sylvester I (314-335 A.D.) who approved Emperor Constantine the Great’s AD 321 edict - changing the Sabbath from Saturday to Sunday.”
My sentence makes sense. Yours? Not so much.