Saturday is the seventh day(Exodus 20:8-11) of the week. Therefore this is the day that God expects all of us to keep Holy. Sunday is actually the first day of the week. The majority of Christians are going to Church on the wrong day. You can't make Sunday what God never intended it to be. Sabbath is God's Holy day(Luke 4:16). Sunday is a man made Holy day not based on Holy Scripture.

Yes Indeed:-) but you will recv' many answers that reject this for lack of Seeking His Truths for themselves instead buying everything their clergy say, hook, line and SINKER, they have excuse after excuse to coat the willful abandonment of Gods Holy Day:-(
excerpt from Rome's Challenge:
in the present article we propose to investigate carefully a new (and the last) class of proof assumed to convince the Biblical Christan that God had substituted Sunday for Saturday for His worship in the new law, and that the divine will is to be found recorded by the Holy Ghost in apostilic writings.
We are informed that this radical change has found expression, over and over again, in a series of texts in which expression, "the day of the Lord," or the Lord's day." is to be found
The class of texts in the NT, under the title"Sabbath" numbering sixty-one in the Gospels, Acts and Epsitles; and the second class in which "the first day of the week." or Sunday, having been critically examined (the latter class numbering nine [eight]; and having been found not to afford the slightest clue to a change of will on the part of God as to His day of worship by man, we now proceed to examine the third and last class of texts relied on to save the Biblical system from the arraigment of seeking to palm off on the world, in the name of God, a decree for which there is not, the slightest warrant or authority from their teacher, the Bible.

another excerpt pg. 11 of Rome's Challenge
But alas! we are once mored doomed to disappointment. Nine times do we find the Sabbath referred to in the Acts, but it is the Saturday (the old Sabbath). Should our readers desire the proof, we refer them to chapter & verse 15:21; again Acts 16:13, 17:2; 18:4 "And he [Paul] reasoned to the synogague every Sabbath, and pursuaded the Jews and the Greeks." Thus the Sabbath (Saturday) from Genesis to Revelation!!! Thus it is impossible to find in the New Testament the slightest interference by the Saviour or His apostles with the Original Sabbath, but on the contrary, an entire acquiescence in the original arrangement; nay, a plenary indorsement by Him, whilst living; and an unvaried, active participation in the keeping of that day and no other by the apostles, for thirty years after His death, as the Acts of the Apostles has abundantly testified to us.
Hence the conclusion is inevitable; viz., that of those who follow the Bible as their guide, the Israelites and Seventh Day Adventists have the exclusive weight of evdience on their side, whilst the Biblical Protestant has not a word in self defense for his substitution of Sunday for Saturday. More anon.
there is plenty more of course, perhaps google for "Romes Challenge"

Sunday is our "mark" of authority...the church is above the Bible, and the transferrence of the Sabbath day observance is proof of that fact. Catholic Record, Ontario, London, Sept. 1, 1923