The TRUTH... Sabbath

Wow! I just had my first Bible study today and I am really motivated to share with you about GOD's precious promise that has it's origination from GOD's creation work.
If you ask anyone in the the world what their favorite/lucky number is, 9 out of 10 times they will tell you the number 7. Why? This number has a special significance in the Bible. From the creation of the world, in
Genesis 2:1-3, we can clearly see the origination of the Sabbath day>7th day> Saturday. But how? On the 7th day, GOD promised three very important things: Rest, blessings and holiness. When we proceed even further in Exodus 20:8-11 (the 4th Commandment), GOD empahsizes the 7th day again naming it the Sabbath day. What is very unique about the first word of the 4th commandment is when GOD tells us to "Remember the Sabbath day by keeping it holy." GOD does not want us to forget the Sabbath day.
We understand that the 7th day is the Sabbath day but how does the 7th day equate to Saturday? Thru the calendar, dictionary and most importantly the Bible, the 7th day IS Saturday. In Mark 16:9, Jesus Christ rose (resurrected) on the first day (Sunday) of the week. For further clarification, in Mark 16:1-2, the Sabbath (7th day) was over... and in verse 2, then the first day (Sunday) of the week came. Wow, this is truly amazing! Without a doubt, GOD said that the promise of rest, blessings and holiness is on the Sabbath day>7th day> Saturday.
Although this message is so clear, then why do so many worship on Sunday the first day of the week? In John 8:47, in order for us to belong to GOD, we must hear what GOD says. Therefore, since GOD said that the Sabbath day>7th day is Saturday , I want to hear what GOD says because I want to belong GOD.
Thank GOD for allowing me this fundamental understanding.