For me it is a matter of obedience. It is a well known fact that the seventh day Sabbath instituted by God at creation is, according to our modern calendar, Saturday. (Or, in these other languages – Arabic: Sabet Armenian: Shabat Bosnian: Subota Bulgarian: Sabota Corsican: Sàbatu Georgian: Sabati Greek: Savvato Indonesian: Sabtu Italian: Sabato Latin: Sabbatum Polish: Sobota Portuguese: S ábado Russian: Subbota Slovak: Sobota Somali: Sabti Spanish: Sabado. Source: http://www.ucg.org/booklet/sunset-sunset-gods-sabbath-rest/sabbath-beginning/names-saturday-many-languages-prove-which-/)
God commanded Israel to keep the Sabbath. There are many bible verses highlighting this command but here is just one for now – Exodus 31:13 “Speak also to the children of Israel, saying: ‘Surely My Sabbaths you shall keep, for it is a sign between Me and you throughout your generations, that you may know that I am the Lord who sanctifies you.” Something to note here is that He commanded the children of Israel – not only the tribes of Judah and Benjamin and some Levites where the Jews as we know them descend from. This command is also for the descendants of Reuben, Simeon, Issachar, Dan, Gad, Asher, Naphtali, Zebulun and Joseph (Ephraim & Manasseh). Here I can also discuss where the descendants of these tribes are throughout the world today, but that is a whole other topic. There are some great resources available to look into – here is one just to whet your appetite http://www.tomorrowsworld.org/booklets/the-united-states-and-great-britain-in-prophecy).
The mainstream tradition of Sunday being a day of worship stems from Pagan ideas. This is no secret. One can talk about Emperor Constantine for a start and the old Babylonian sun-god known in Roman times by his Persian name of Mithra (click here to read an excellent article delving into this topic http://www.tomorrowsworld.org/magazines/2013/jan-feb/the-mysterious-mark-of-the-beast). This subtlety of deception has influenced main-stream Christians into thinking they are worshipping the true God while all time they are inadvertently adhering to pagan sun worship.
Why is God’s church considered a “little flock” (Luke 12:32) – could it be that true seventh-day Sabbath keeping is one of the signs of God’s true church? In Ezekiel 20:12 God says “Moreover I also gave them My Sabbaths, to be a sign between them and Me, that they might know that I am the Lord who sanctifies them”. How beautiful and what a gift! Jesus Christ showed love to His Father by obeying His command to keep the Sabbath. (“If you love Me, keep My commandments” John 14:15). He did not just follow a “Jewish tradition”. Shouldn’t we do the same? If Jesus Christ did it, so should we.
Some people will find arguments to justify the change of the Sabbath to the first day of the week, just to make them feel like they are doing the right thing. But that is what we humans are pretty good at doing – justifying ourselves because we don’t want to be proven wrong. But the evidence is clear – God instituted the Sabbath, He commanded ALL people to keep it throughout all generations, Jesus Christ set us the example to follow, if we love God we will keep (obey) His commandments, and mainstream Sunday keeping has its roots founded in the worship of Babylonian false gods. Here is an interesting warning from the book of Deuteronomy about worship of the creation (for example, the sun) rather than the Creator “And take heed, lest you lift up your eyes to heaven, and see the sun, the moon, and the stars, all the host of heaven, you feel driven to worship them and serve them” (Deuteronomy 4:19).
The true seventh day Sabbath is a blessing from God for all of mankind. Obeying His commandment to “remember the Sabbath day and keep in Holy” (Exodus 20:8) is a sign that we love our Creator and desire to serve Him. History shows clearly that the god of this world has set up a mass deception by promoting Sunday worship. I could go into all this further, but others have already done that for me so instead I will give you a bunch of links that I recommend you look into and study up for yourself. If you don’t want to read “church literature” then just look it up on Wikipedia – the history behind it all isn’t a secret.
(See this article by CBCG for some expansion of this topic http://www.cbcg.org/franklin/SA/SA_sunday.pdf)