The Sabbath, Worship, and the Day Change

One of the arguments for the day change of the Sabbath from the seventh day of the week to the first day of the week is that the New Testament emphasizes the first day of the week as the day Christians met for public worship:

“On the first day of the week, when we were gathered together to break bread, Paul talked with them, intending to depart on the next day, and he prolonged his speech until midnight.” (Acts 20:7)

“Now concerning the collection for the saints: as I directed the churches of Galatia, so you also are to do. 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 there will be no collecting when I come.” (1 Corinthians 16:1, 2) (cf. John 20:19, 26)

Now, someone might say, “How does Christians meeting for public worship on the first day of the week imply a day change in the Sabbath?  Where does the Bible say the Sabbath was ever a day for public worship?”  

To this we reply with the following:

1. Leviticus 23:3 reads:

“Six days shall work be done, but on the seventh day is a Sabbath of solemn rest, a holy convocation. You shall do no work. It is a Sabbath to the LORD in all your dwelling places.”

On “holy convocation,” Matthew Henry writes:

2. On that day they must employ themselves in the service of God. (1.) It is a holy convocation; that is, "If it lie within your reach, you shall sanctify it in a religious assembly: let as many as can come to the door of the tabernacle, and let others meet elsewhere for prayer, and praise, and the reading of the law," as in the schools of the prophets, while prophecy continued, and afterwards in the synagogues. Christ appointed the New-Testament sabbath to be a holy convocation, by meeting his disciples once and again (and perhaps oftener) on the first day of the week.

(2.) "Whether you have opportunity of sanctifying it in a holy convocation or not, yet let it be the sabbath of the Lord in all your dwellings. Put a difference between that day and other days in your families. It is the sabbath of the Lord, the day on which he rested from the work of creation, and on which he has appointed us to rest; let it be observed in all your dwellings, even now that you dwell in tents." Note, God's sabbaths are to be religiously observed in every private house, by every family apart, as well as by many families together in holy convocations. The sabbath of the Lord in our dwellings will be their beauty, strength, and safety; it will sanctify, edify, and glorify them.
Matthew Henry, Commentary on the Whole Bible: Volume 1: Leviticus Chapter 23

Jesus attended public worship on the Sabbath:

^“And they went into Capernaum, and immediately on the Sabbath he entered the synagogue and was teaching. And they were astonished at his teaching, for he taught them as one who had authority, and not as the scribes.” (Mark 1:21, 22)

“And on the Sabbath he began to teach in the synagogue, and many who heard him were astonished, saying, "Where did this man get these things? What is the wisdom given to him? How are such mighty works done by his hands?” (Mark 6:2) (cf. Luke 4:16; 6:6; 13:10)

We are told it was Christ’s custom to meet for worship on the Sabbath:

“And he came to Nazareth, where he had been brought up. And as was his custom, he went to the synagogue on the Sabbath day, and he stood up to read.” (Luke 4:16)

3. And, finally, the word of God was publicly proclaimed on every Sabbath: 

“For from ancient generations Moses has had in every city those who proclaim him, for he is read every Sabbath in the synagogues.” (Acts 15:21)