First of all, let us look for the meaning of the Sabbath according to Easton’s Bible Dictionary 1897 the word “Sabbath”.
It comes from the Hebrew word “Shabbath” meaning “To rest from labour”. BibleStudyTools
The Sabbath of the Jews is on the Seventh Day or Saturday in our Gregorian calendar and Sabbath of the Christian is on the First day which is Sunday in our calendar.
For us Christians, first day or Sunday is very important because this is the day when Jesus Christ Resurrected. If Jesus Christ did not resurrect Christianity is nothing.
“If Christ has not been raised, then our preaching is in vain and your faith is in vain.” – 1 Corinthians 5:14.
The gathering of the Christians, according to the Bible is on the First day which is Sunday.
“On the FIRST DAY of the week, when we were gathered together to break bread, Paul talked with them, intending to depart on the morrow; and he prolonged his speech until midnight.” – Acts 2:7.
The truth, when Paul talked to them, they just do it at the same time for their weekly gathering.
“On the FIRST day of every week, each of you is to put something aside and store it up, as he may prosper, so that contributions need not be made when I come.” – 1 Corinthians 16:2.
See? But actually in other Translation like the Good News Bible you will see the word “Sunday”.
“Every Sunday each of you must put aside some money, in proportion to what you have earned, and save it up, so that there will be no need to collect money when I come.” – 1 Corinthians 16:2.
Now why the collection is on the First day, which is Sunday?
Because the Christians when the time of the Apostles, they are gathering on the First day, which is Sunday and not the Seventh Day or Saturday. Just like the Seventh day Adventist claim. We will see that the true followers of Jesus do gathering on Sunday not Saturday. The one who gathered and prioritize the Saturday or Seventh Day is only the Jews.
The fact is the bible tells us that Christians did not work in the Seventh Day. Then Seventh Day Adventist and Other Anti-Catholics who follow the Jewish Law are always judging and criticize Catholics because we worship on Sunday instead on Saturday.
But always remember what St. Paul said:
“Let no man therefore judge you in meat or in drink, or in respect of a festival day, or of the new moon, or of the Sabbaths.” – Colossians 2:16
Until now there are many criticizing the Catholics because we worship on Sunday instead of Saturday and also they said that the Catholic Church change the Sabbath Day from Saturday to Sunday etc.
The Adventist has an issue regarding the Sabbath day they kept telling the world through social media that the Catholic Church changed the Sabbath day into Sunday.
But it is not true because the Fact is before the Catholic Church Founded by Our Lord Jesus Christ the Sunday worship is already happening.
“On the FIRST day there will be a holy assembly. Don’t do any regular work.” – Leviticus 23:7.
We should understand that at the time of the Jews the calendar has no specific name yet. The days simply called First Day, Second Day etc.
We should remember also that the Sabbath day is to “rest” and that is the teaching of Our Lord Jesus Christ that the Sabbath day is Sunday. It is very clear that no one changed the Sabbath day from Seventh Day (Saturday) to First Day (Sunday). Their understanding about the scripture is really poor they did not understand that the Sabbath day is not limited only in the Seventh Day.
When Jesus Christ became man he already corrects that understanding.
“And Jesus concluded, “The Sabbath was made for the good of human beings; they were not made for the Sabbath.” – Mark 2:27.
For the Jews who did not recognize the Lord Jesus Christ their rest day is still the Seventh day which is Saturday.
The Question is why does Jesus Christ did not gather with the Apostles and other Christians on the Seventh Day? Because they gather on the First day, which is Sunday.
“Then the same day at evening, being the FIRST day of the week, when the doors were shut where the disciples were assembled for fear of the Jews, came Jesus and stood in the midst, and saith unto them, Peace be unto you. – John 20:19.
See actually in other translation like in the Good News Translation you will see again the word Sunday.
“It was late that Sunday evening, and the disciples were gathered together behind locked doors, because they were afraid of the Jewish authorities. Then Jesus came and stood among them. “Peace be with you,” – John 20:19.
Remember this verse also:
“So they began harassing Jesus as a Sabbath Breaker.” – John 5:16 Living Bible (TLB).