1st day of the week : Sunday or Saturday or Monday?

I was over at a Bible Presbytarian Church in central attending night classes on Apostle Paul and his life as a missionary to the gentiles. Not going to touch in depth on what I learn today though!

In particular, what I'm going to touch on is a nitty gitty issue, not a law, not a commandment but just a practice, an idea. When is the first day of the week according to the Bible? Saturday? Sunday? Or monday?

Let's begin with from the start, we saw that the world was made in 7 days and on the 7th day, the Bible says :

Genesis 2:2-3

²And on the seventh day God ended his work which he had made; and he rested on the seventh day from all his work which he had made.

³And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made.

Fact : The seventh day is the sabbath as God had blessed the seventh day and sactified it.

Assumptions : Seventh day is sunday. First day is monday. However, scripture does not say anything mondays to sunday.

Current situation : All we know is that for Christians, service is on sunday. For the jews who still lived in the OT literally, their sabbath is on saturday.

The following verses confirm that the sabbath is actually on saturday and that sunday, the day of service in rememberance of Christ is the first day of the week.

Matthew 28

¹In the end of the sabbath, as it began to dawn toward the first day of the week, came Mary Magdalene and the other Mary to see the sepulchre.

End of the saturday sabbath, as it dawns towards sunday, the first day of the week, the Marys found the grave empty and that Christ has rose from the dead.

Acts 20:7
⁷And upon the first day of the week, when the disciples came together to break bread, Paul preached unto them, ready to depart on the morrow; and continued his speech until midnight.

Breaking bread referring to the holy communion which is on sunday always, the day Christ rose from the dead. This would be very clear that the holy communion held on sunday, is the first day of the week.

However, all this is just really, not very important. The main thing is :

Romans 14:5
“One man considers one day more sacred than another; another man considers every day alike. Each one should be fully convinced in his own mind” .

We are to worship God every day, not just on Saturday or Sunday.

Articles regarding the Sabbath in detail : What day is the Sabbath?