King James Bible
John 14:6
Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
If you pray to anyone other than Christ you are supporting the Catholics Pantheon of Gods and NOT Monotheism.
The core beliefs of the Holy Roman Catholic Church were developed by the Council at Nicea, Which was Commissioned by the Pagan King Constantine.
Before Constantine and Christianity, Rome had a Pantheon of Gods. Constantine Hybridized the existing Roman Religion with Christianity to form The Holy Roman Catholic Church.
At that point Constantine became a “Christian”.
So how exactly does Praying to Mary make one a Christian?
You wrote:
“Before Constantine and Christianity, Rome had a Pantheon of Gods.”
In case you didn’t know, Rome had a pantheon of gods AFTER Constantine as well. Most Romans were still pagans. Strange that they didn’t know that Constantine had created what you claim here:
“Constantine Hybridized the existing Roman Religion with Christianity to form The Holy Roman Catholic Church.”
That’s just about too stupid an idea for words - and that’s probably why no modern reputable historian believes that.
“At that point Constantine became a “Christian”.”
No, actually Constantine became a Christian in belief BEFORE he was even emperor. Thus, he believed in Christ and His Church BEFORE he even had the power or authority to do anything to any religion.
“So how exactly does Praying to Mary make one a Christian?”
In itself it doesn’t. It also doesn’t make one unchristian.
Do something for us. Go back in history and find the howls of protest from the Christians who were actually there, at the time, and saw this alleged syncretism take place.
You won't find any. That's because it didn't happen that way.
The big argument in Constantine's day was whether Jesus was true God, or some created superbeing less than God, not whether one ought to pray to Mary.
(As far as the "is Jesus true God" argument goes: Constantine, at least in some accounts, was on the losing side of that issue, BTW. Not the side that carried the day for Catholicism, Orthodoxy, and Protestantism.)
Constantine's second successor was his half-nephew, a man named Flavius Claudius Julianus, known to history as "Julian the Apostate". He got his moniker because he devoted his entire career to doing everything possible (short of actual persecution -- he knew that wouldn't work) to end Catholic Christianity in the Empire, and restore paganism.
Evidently he didn't see the sycretism you say happened, and he lived through the era in which you claim it occurred.