The Bible does not say that Sunday is the 7th day. It says that Saturday, the Sabbath, is the 7th day. And that Jesus rose on the day after the Sabbath, which means it was on the first day of the week. And that's the day most Chistians have adopted as their day of worship. (Except Seventh Day Adventists who keep it, as their name suggests, on the 7th day: Saturday.)

If your church preaches differently, they should read their Bible more carefully.

Seventh‐day Adventists are definitely the most prolific Christian keepers of a Saturday sabbath, but they are not totally alone. The next most prominent groups I can think of are Seventh Day Baptists and Messianic Jews. SDAs are in the tens of millions worldwide, Messianics in perhaps the hundreds of thousands, and SDBs under one hundred thousand.

Although they’re fairly distinct traditions, in my experience each places great importance on religious liberty and separation of church and state, because historically all three groups have faced governmental persecution from blue laws. SDAs go so far as to believe Revelation’s mark of the Beast refers to a blue law to come in the future.

Messianics also have been known to face religious persecution in Israel. To the extent Christianity is viewed with mistrust by Judaism due to Christendom’s history of persecuting Jews, Messianic Judaism is further seen as an attempt by Christians to co‐opt or corrupt Jewish practices.

(Another fun fact: Seventh‐day Adventists hyphenate their name, but Seventh Day Baptists don’t.)

And not event that far, sabbath (Saturday) is determined to be the 7th day of the week at the start of Genesis.

We also have "bookends" which go on both sides of the books they support. That's kinda how I see "weekends".

"Sat and Sun constitute the weekEND, right?"

It's called a bookEND only if it's to the right of the row of books. If it's to the left (for books in an RTL language), we call it a bookSTART

There are two bookends in every matching set - one for each end of the row of books.

6-day work weeks are still common in agriculture, and the Bible is silent on what the exact weekday the sabbath lands on. Some people really argue that it's supposed to be Saturday, but traditionally Jesus's resurrection is said to have happened on Sunday, so most Christian churches went along with that.

My own personal opinion: it matters not what day you consider to be the sabbath, but it does help when a community agrees on a day and goes along with it. So for me, Sunday it is. (It also doesn't matter how a calendar is printed; it could start on Wednesday for all I care. It'd be weird, but it wouldn't change anything.)

The day of the sun, or the Lord's day, is not the 7th day sabbath, it was declared by the Catholic Church to supersede the Sabbath and celebrate the resurrection instead.

In saying “the Sabbath . . . has been replaced by Sunday” (CCC 2190), the Church does not dismiss the significance of the Sabbath. The Catechism reminds us, “Sunday is expressly distinguished from the Sabbath which it follows chronologically every week” (CCC 2175).

https://www.catholic.com/magazine/print-edition/the-lords-da...

As for which day is the 7th, you can check with descendants of the good book's authors, still around, and still keeping count. The Jewish faith hasn't lost track.

Thanks, that's good info :) I definitely have new things to study and ponder about.

I'm of the Latter-day Saints tradition and we basically use Lord's Day and Sabbath interchangeably, though I'm speaking anecdotally and from casual use. I may very well be using it incorrectly!

IIRC it was very common for early Christians, who were mostly Jews initially, to go to temple on the Sabbath (Saturday) and then have their own meetings on Sunday, as they didn’t consider them separate.

I think we can trust the Jews to have kept the Sabbath fairly consistently. The Christians literally changed their reserved day of the week in honour of Jesus' resurrection. Luckily the fact that this was the day after the sabbath is completely unambiguously pinned down in the Bible.