Your assertion is a smidgeon of fact with a huge admixture of error and distortion. By this time, the Sunday Lord's Day was well established by Christians, in fact, from New Testament times. Constantine issued his edict (a civil one, not a religious one from the Church or a Pope) as a means to keep unity in his empire by making Sunday the Lord's day a civil law. This was done to combat, among other things, the Sol Invictus cult, not to complement it.
What is your source on this? And yes, you are correct that Constantine issued his edict as a means to keep unity in his empire by making Sunday the Lord's day a civil law. But this was a civil and a religious law in collaboration with Rome. This was an unholy mixture of pagan and papal brew to keep the natives pacified. By combining the Sol Invictus cult AND Christianity together, you have a larger audience with more lucre for the Church coffers.
Satan is the ruler of this world and can offer money and power to achieve his goals and he hit a homerun here. James 2:10 For whoever shall keep the whole law, and yet stumble in one point, he is guilty of all. Brilliant. And the whole world follows Rome.
_____By this time, the Sunday Lord’s Day was well established by Christians, in fact, from New Testament times.____
A single text from the Bible that shows the Seventh day Sabbath commandment in stone was changed. And a lunch by the disciples on the first day don’t count. That’s laughable and you know it. Even Rome’s challenge, YOUR OWN CHURCH mocks that assertion.
just one text.....show me.