"So...here we are 2000 years later, wondering how a Jewish based religion suddenly moved it's Sabbath from the seventh day (as it should be) to the first day of the week that was named for the SUN. (Sol-Invictus)"
Why "should" it be on Saturday?
We're not Jews.
The Christians didn't move their celebration day to Sunday in the 150s. They were celebrating the Lord's Day in the First Century. They celebrated on Sunday because that was the day Jesus was Resurrected, an astounding event.
If God was offended by this, you would think that he would have told them. But he did no such thing. Instead, he continued to shower them with blessings and graces.
If God doesn't care, who are we too?
"If God doesn't care, who are we too?"
Genesis 2:2
Leviticus 23:3
Deuteronomy 5:12
Those verses would lead one to believe that He does care.