You can blame the Catholic Church for many things, but the Lord's Day [the first day of the week, which is commonly called Sunday (the day of the sun)] was established in Scripture, and in the apostolic churches, as the day of rest and worship. In effect it is the Christian Sabbath. Please note (Rev 1:10): I was in the Spirit on the Lord's day, and heard behind me a great voice, as of a trumpet.
Is it not significant that John was "in the Spirit" (under the Holy Spirit's control) on "the Lord's Day". Why "the Lord's Day"? Because it was the Day of Resurrection, and the Morrow after the Sabbath (the 8th day is the day of beginning of a new week as well as the beginning of a New Creation). Check out the significance of the number 8.
So the short answer is that when the SDA's blame Constantine and the Catholic Church, they simply ignore Scripture. Apostolic churches were meeting on the first day of the week to Break Bread (the Lord's Supper).
Let's look at Revelation 1:10:
The many times that the "Sabbath" of the LORD is given in the New Testament:
Matthew 12:1,2,5,8,10,11,12, 24:20, 28:1;
Mark 1:21, 2:23,24,27,28, 3:2,4, 6:2, 7:6-9, 15:42, 16:1;
Luke 4:16,31, 6:1,2,5,6,7,9, 13:10,14,15,16, 14:1,3,5, 23:54,56;
John 5:9,10,16,18, 7:22,23, 9:14,16, 19:31;
Acts 1:2, 13:14,27,42,44, 15:21, 16:13, 17:2, 18:4;
Additional references are:
Hebrews 4:9; [Greek: sabbatismos, literal sabbath-keeping]
Revelation 1:10 [kuriake hemera, "the Lord's Day" [the 7th Day Sabbath, not "the Day of the Lord", this is totally different in the Greek], see Genesis 2:1-3, Exodus 20:8-11, Deuteronomy 5:12:15, Isaiah 58:13, 66:23, Matthew 12:8, Mark 2:27,28; Luke 6:5 ],
10:6 [see also Exodus 20:11, 31:17 Nehemiah 9:6; Psalms 146:6; Acts 4:24, 14:15, Revelation 14:7];
14:7 [see previous], etc
Additionally, further references in the Greek are [every single 'first [day] of the week' text]:
Matthew 28:1a - oye de sabbatwn
Matthew 28:1b - eiV mian sabbatwn
Mark 16:2 - kai lian prwi ths mias sabbatwn
Mark 16:9 - anastas de prwi prwth sabbatou
Luke 24:1 - th de mia twn sabbatwn
John 20:1 - th de mia twn sabbatwn
John 20:19 - th mia twn sabbatwn
Acts 20:7 - en de th mia twn sabbatwn
1 Corinthians 16:2 - kata mian sabbatwn
Additional reference is in the Sabbath before Jesus' death, wherein Jesus, the disciples and Lazarus, all were at Lazarus' house, six days before the Passover, the very next day being the Triumphal entry:
Then Jesus six days before the passover came to Bethany, where Lazarus was which had been dead, whom he raised from the dead. John 12:1
The Church met many days of the week in Acts, yes even in the Gospels and elsewhere, the Christians [even as did the Jews] met daily, none of which eliminates obedience to God in His 4th Commandment, at all, as we see them [the Church, Jews & Gentiles] explicitly meeting on "the Sabbath" hundreds of times in the NT alone, even "in the grace of God".
Jesus met in the temple "daily" [and not only there, also synagogue, and in nature], even especially in his last week from Sunday to Tuesday, especially: John 11:55, 21:1; Matthew 26:55; Mark 14:49; Luke 19:47, 22:53; John 18:20; see additionally [in this order, read carefully], Matthew 21:10; Mark 11:11; John 12:12,13; Matthew 21:12,13,17; Mark 11:12,15,16,17,19; Matthew 26:2; Mark 14:1; Matthew 21:18,23; Mark 11:20,27; Matthew 23:37,38,39 [Parallel to Luke 13:31,32,33,34,35] And they, continuing
daily with one accord in the temple, and breaking bread from house to house, did eat their meat with gladness and singleness of heart, Acts 2:46
And daily in the temple, and in every house, they ceased not to teach and preach Jesus Christ. Acts 5:42
And does any know why this "daily"? Understand this text - Psalms 77:13
Also, Jesus met with the Discples the 2nd day of the week here, since he spent a great deal of time with the two Disicples on the Road to Emmaus on the first day [see Luke 24:21, "...beside all this,
to day is the third day since these things were done"], it came to be evening [which begins the next day, when the sun sets at even, Mark 1:32; Leviticus 23:32; Genesis 1:5,8,13,19,23,31, etc ], and then they sat down to dinner, and as Jesus vanished before them, they ran back to Jerusalem at night and then Jesus met with them again, all together [thus no longer the 'first [day] of the week', but rather the second [day] of the week]:
But they constrained him, saying, Abide with us: for it is toward evening, and the day is far spent. And he went in to tarry with them. Luke 24:29
And it came to pass, as he sat at meat with them, he took bread, and blessed it, and brake, and gave to them. Luke 24:30
Andthey rose up the same hour, and returned to Jerusalem, and found the eleven gathered together, and them that were with them, Luke 24:33
And as they thus spake, Jesus himself stood in the midst of them, and saith unto them, Peace be unto you. Luke 24:36
Jesus also stayed for 40 days after His resurrection, His first ascension and return:
To whom also he shewed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God: Acts 1:3
Thus, since Jesus ascended for the Second time, this time from the Mount of Olives, he was there with them exactly 10 days before Pentecost [first [day] of the week], which means, we see again that Jesus was with them not merely upon the first [day] of the week.
Paul and Barnabas, and Luke, etc not only met in the synagogue [which simply means "the gathering"], but also outdoors in nature, God's Creation, just as Jesus had done, and reading/teaching the Scriptures and speaking of the Gospel as Jesus had done while He kept the 7th Day Sabbath:
And he came to Nazareth, where he had been brought up: and,
as his custom was, he went into the synagogue on the sabbath day, and stood up for to read. Luke 4:16 [What was Jesus reading about?]
And there was delivered unto him the book of the prophet Esaias. And when he had opened the book, he found the place where it was written, Luke 4:17
And he closed the book, and he gave it again to the minister, and sat down. And the eyes of all them that were in the synagogue were fastened on him. Luke 4:20
At that time Jesus went on the sabbath day through the corn; and his disciples were an hungred, and began to pluck the ears of corn, and to eat. Matthew 12:1
And they went into Capernaum; and straightway on the sabbath day he entered into the synagogue, and taught. Mark 1:21
And it came to pass, that he went through the corn fields on the sabbath day; and his disciples began, as they went, to pluck the ears of corn. Mark 2:23
And when the sabbath day was come, he began to teach in the synagogue: and many hearing him were astonished, saying, From whence hath this man these things? and what wisdom is this which is given unto him, that even such mighty works are wrought by his hands? Mark 6:2
And came down to Capernaum, a city of Galilee, and taught them on the sabbath days. Luke 4:31
And it came to pass on the second sabbath after the first, that he went through the corn fields; and his disciples plucked the ears of corn, and did eat, rubbing them in their hands. Luke 6:1
And it came to pass also on another sabbath, that he entered into the synagogue and taught: and there was a man whose right hand was withered. Luke 6:6
And he was teaching in one of the synagogues on the sabbath. Luke 13:10
And it came to pass, as he went into the house of one of the chief Pharisees to eat bread on the sabbath day, that they watched him. Luke 14:1
And Paul, as his manner was, went in unto them, and three sabbath days reasoned with them out of the scriptures, Acts 17:2
And on the sabbath we went out of the city by a river side, where prayer was wont to be made; and we sat down, and spake unto the women which resorted thither. Acts 16:13
What did Paul,etc do that Jesus didn't do? Didn't Jesus preach the Gospel [Isaiah 61]? Notice the context of the last verse, it was where "prayer" was made, and they "sat down".
Jesus specifically foretold that the Christians would be keeping the Sabbath long after He had ascended, even as they continued to do, even after He died:
And they returned, and prepared spices and ointments; and rested the sabbath day according to the commandment. Luke 23:56
Then returned they unto Jerusalem from the mount called Olivet, which is from Jerusalem a sabbath day's journey. Acts 1:12 [This was written by Luke, a Gentile, years after the fact]
But pray ye that your flight be not in the winter, neither on the sabbath day: Matthew 24:20
The Gentiles themselves, as it was foretold in the OT, begged Paul to preach to them also on the Sabbath:
And when the Jews were gone out of the synagogue, the Gentiles besought that these words might be preached to them the next sabbath. Acts 13:42
And the next sabbath day came almost the whole city together to hear the word of God. Acts 13:44 [That was primarily from the Old Testament, aided by the Testimony of Jesus]
Further, we see that Paul preach in specific places, always on the Sabbath to the peoples, Jews and Gentiles, even in one city a year and six months, every Sabbath!
And Paul, as his manner was, went in unto them, and three sabbath days reasoned with them out of the scriptures, Acts 17:2
And he reasoned in the synagogue every sabbath, and persuaded the Jews and the Greeks. Acts 18:4
As for "the Lord's Day" of Revelation 1:10, consider the context itself.
It is an historical statement, in historical context, and refers directly to the "word of God", and the "testimony of Jesus Christ". This refers to the Ten Commandments themselves, as may be shown for those that desire to see it.
Furthermore, the context and language of the Greek refers to other various passages in Scripture itself, none of which are speaking about "Sunday", but instead
always the 7th Day the Sabbath of the LORD thy God, His Holy Day, which is the very heart and center of His Moral Law of Ten Commandments.
I was in the Spirit on
the Lord's day...Revelation 1:10
egenomhn en pneumati en
th kuriakh hmera... Revelation 1:10 [Greek Tr; Stephen's 1550 TR]
The Greek specifically says, "en th kuriakh hmera".
The Greek thus reads in "ownership" [ie, it [the day itself] is His, and He owns it and He is "Lord" of it], for John was "in the Spirit" "on" [that is, 'in the midst of'] "the" [definite article; specific] "Lord's" [it is His, He owns it] "day".
[see: "Remember
the sabbathday, to
keep it holy." Exodus 20:8; "Six days shalt thou labour, and do all thy work:" Exodus 20:9; "But
the seventh day [is]
the sabbath of the LORD thy God: [in it] thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that [is] within thy gates:" Exodus 20:10; "For [in] six days
the LORD made heaven and earth, the sea, and all that in them [is], and rested
the seventh day: wherefore
the LORD blessed
the sabbath day, and
hallowed it." Exodus 20:11and also, "Keep
the sabbath day to
sanctify it, as
the LORD thy God hath commanded thee." Deuteronomy 5:12; "Six days thou shalt labour, and do all thy work:" Deuteronomy 5:13; "But
the seventh day [is]
the sabbath of the LORD thy God: [in it] thou shalt not do any work, thou, nor thy son, nor thy daughter, nor thy manservant, nor thy maidservant, nor thine ox, nor thine ass, nor any of thy cattle, nor thy stranger that [is] within thy gates; that thy manservant and thy maidservant may rest as well as thou." Deuteronomy 5:14; "And remember that thou wast a servant in the land of Egypt, and [that]
the LORD thy God brought thee out thence through a mighty hand and by a stretched out arm: therefore
the LORD thy God commanded thee to
keep the sabbath day." Deuteronomy 5:15]
Notice in the so-called LXX, Septuagint, see Exodus 20:8-11; Deuteronomy 5:12-15
We see from those passages in the so-called LXX and standard English [from the Hebrew], that "...the seventh day [is] the Sabbath of..." [ownership, it is His, "of"] "...the Lord thy God..."; and therefore He, being its maker, is the Lord of this Day of which He sanctified [set it apart from all other days in use for a specific and distinct purpose], hallowed [made it Holy], ceased from Creation [in the previous 6 days] and rested in it, the [definite article, specific] 7th Day.
Let's see that in Revelation 1:10:
["en"] Preposition
["th"] T-DSF - Robinson's Morphological Analysis Codes
Part of Speech: definite article
Case: Dative
Number: Singular
Gender: Feminine
["kuriakh"] A-DSF - Robinson's Morphological Analysis Codes
Part of Speech: Adjective
Case: Dative
Number: Singular
Gender: Feminine
["hmera"] N-DSF - Robinson's Morphological Analysis Codes
Part of Speech: Noun
Case: Dative
Number: Singular
Gender: Feminine
John was
not referencing "the day of the Lord" [2nd Advent; beginning the Millennium [1,000 years] directly by this term, as that is the 7th Day
with the LORD, being the 7th Millenium, this earth being 6,000 years old already] [see 1 Corinthians 5:5 ["en th hmera tou kuriou ihsou"]; 1 Thessalonians 5:2 ["h hmera kuriou"]; 2 Peter 3:10 ["de h hmera kuriou"], etc] in Revelation 1:10, for that reads differently throughout the scriptures and additionally the very context [of Revelation 1] excludes it.
Also John saw the past, present and future throughout [Revelation 1:19], which in Revelation 1-3, would include the 7 churches, which are not begun with the 1,000 years, but are part of the 6,000 year history, and therefore John was not in the Millennium seeing the Church ages.
John is also not referencing the "first [day] of the week", as this always in the scripture is merely a day pointing to the culmination of the week, the 7th Day the Sabbath, as the other 5 of the 6, that points unto the 7th in every single instance.
In the First Day, there is incomplete and unfinished work [more work to be done], but in the 7th, the work is complete and finished [there is rest from work].
See this in 1 Corinthians 5:5; 1 Thessalonians 5:2; 2 Peter 3:10 in the GReek.
["kuriou"] N-GSM - Robinson's Morphological Analysis Codes
Part of Speech: Noun
Case: Genitive
Number: Singular
Gender: Masculine
See also the OT Hebrew and so-called LXX [example Isaiah 13:6; etc]:
HYLYLV KY QUrVB YVM YHVH KShD MShDY YBV'a. Isaiah 13:6
Again, ["kuriou"] N-GSM, not the same as ["kuriakh"] A-DSF.
Therefore, we can easily go throughout the scriptures and make the same comparisons. "the Lord's day" that we are dealing with in Revelation 1:10, is not what the rest of scripture terms "the day of the Lord", though it does help us to understand that which is coming. What then is it? Well, we let the scriptures define it for us, and we do not have to guess. ...
...So, let us go to other scriptures which declare that Jesus is "Lord" "of" "the Sabbath Day", "the 7th Day":
For
the Son of man is Lord even of the sabbath day. Matthew 12:8
Therefore
the Son of man is Lord also of the sabbath. Mark 2:28
And he said unto them, That
the Son of man is Lord also of the sabbath. Luke 6:5
If thou turn away thy foot from
the sabbath, [from] doing thy pleasure on
my holy day; and call
the sabbath a delight,
the holy of the LORD, honourable; and shalt honour him... Isaiah 58:13
But
the seventh day [is]
the sabbath of the LORD thy God... Exodus 20:10
See Hebrews 4, which reveals which Day God took for Himself, the 7th Day. He rested in it.
John was an Apostle and a Prophet, and He, loving Jesus, kept His Commandments, even upon the Isle of Patmos:
Who
bare record of the word of God, and
of the testimony of Jesus Christ, and of all things that he saw. Revelation 1:2
[see also "For he established
a testimony in Jacob, and appointed
a law in Israel, which he commanded our fathers, that they should make them known to their children:" Psalms 78:5; "To
the law and to
the testimony: if they speak not according to this word, [it is] because [there is] no light in them." Isaiah 8:20; "Yet the LORD
testified against Israel, and against Judah,
by all the prophets, [and by] all the seers, saying, Turn ye from your evil ways, and
keep my commandments [and] my statutes, according to all the law which I commanded your fathers, and which I sent to you by my servants the prophets." 2 Kings 17:13; "Nevertheless they were disobedient, and rebelled against thee, and cast
thy law behind their backs, and slew
thy prophets which
testified against them to turn them to thee, and they wrought great provocations." Nehemiah 9:26; also known as "
the law and
the prophets" [Matthew 5:17, 7:12, 11:13, 22:40; Luke 16:16, 24:44; John 1:45; Acts 13:15, 24:14, 28:23; Romans 3:21, etc]]
Blessed [is] he
that readeth, and they that
hear the words ofthis prophecy, and
keep those things which are written therein: for the time [is] at hand. Revelation 1:3
...and thus John writes to the 7 Churches which are in asia, and then makes the following statement:
I John, who also am
your brother, and
companion in tribulation, and
in the kingdom and patience of Jesus Christ,
was in the isle that is called Patmos,
for the word of God,
and for the testimony of Jesus Christ. Revelation 1:9
...of which
Revelation 1:10 immediately follows...
...and so we see that
Revelation 1:10 is an historical statement, that he [John] was keeping the 7th Day the Sabbath of the LORD [Jesus] and it was upon that specific day that he received the vision. Jesus Christ in His death rested, and thus Salvation and Creation are forever linked in Him, in that Holy Day. Woe unto them that reject the Holy Commandment delivered unto them.
Those who forsook the Commandments of God, His Law, would not receive a vision, for the two are directly related ... "
the law [is] no [more];
her prophets also find
no vision from the LORD."Lamentations 2:9;p, see also Proverbs 29:18; Ezekiel 7:26; Zephaniah 3:4; Zechariah 7:12, etc.
In fact we see again the connection in the Book of Daniel [which the Book of Revelation of Jesus Christ is the sister book of; the two are so inter-related that they are to be read together], we see Daniel [who being faithful] directly stating, "And I prayed unto the LORD my God, and made my confession, and said, O Lord, the great and dreadful God, keeping the covenant and mercy to them that love him, and to them that keep his commandments;" Daniel 9:4 [which is again directly quoting from the Ten Commandments; Exodus 20:6; John 14:15, etc] and he is the one who receives the visions.
These Biblical matters reveal what Day was John speaking about by the Holy Spirit [compare also Revelation 1 language to that of Revelation 22 language and see vs 14, "do his commandments", in conjunction with Revelation 1:10].