Why does the Church of God keep services on Saturday?

Sister, God bless you on the Sabbath day! You’ve come early. We still have much time before the service.
I heard I’d better come earlier than the service time to keep it with a godly mind. I’m a sleepyhead, so getting up this morning was a struggle for me.
I’m happy to see you make efforts to do as you’ve learned!
But you know what? Some people say it’s weird when I tell them I go to church on Saturday. Tilting their heads, they ask me, “Isn’t Sunday the day of worship?”
They did?
Yes. So, I’m asking you, “Why does our church keep services on Saturday unlike other churches?”
The day we’re promised to meet God is the Sabbath day, and it is Saturday. Suppose you make an appointment with an important person, but then you visit him on a different day. Do you think you can meet him? In the same way, the day to meet God is set. If we keep service on the next day after the appointed day, we cannot meet God.
Okay, I see the point. But why did God let us keep the Sabbath day among many days?
You can find the reason when you see the origin of the Sabbath day.

“By the seventh day God had finished the work he had been doing; so on the seventh day he rested from all his work. And God blessed the seventh day and made it holy, because on it he rested from all the work of creating that he had done.” Genesis 2:2–3

Wow! This sounds so grand.
That’s right. God finished His creation work and rested on the seventh day, calling it the Sabbath day. Sabbath means rest. And God made the day as a commandment and let us keep it holy so that we can be blessed by God and become holy.

“Remember the Sabbath day by keeping it holy … Therefore the LORD blessed the Sabbath day and made it holy.” Exodus 20:8–11

If it were okay for us to keep service on any day, God wouldn’t have particularly appointed the Sabbath day. So if anyone wants to worship God truly, he must not change the given day as he likes, but keep it holy as it was told by God.
I can see for sure that the Sabbath is the seventh day. The thing is, even though you tell me the seventh day is Saturday, many people regard Sunday as the seventh day. So I’m a little confused.
People tend to think so because they don’t usually go to work or school on Sunday and begin on Monday. However, the first day of the week is not Monday but Sunday. When you see the calendar, a week begins with Sunday, right? It begins with Sunday because it is the first day of the week. However, common sense may change according to the passage of time. The sure standard that we should have is the Bible that never changes. Through the Bible, we can confirm that the seventh-day Sabbath is Saturday.

Are you saying the Bible explains what day of the week the Sabbath is?
Sure. Shall we take a look?

“When the Sabbath was over … When Jesus rose early on the first day of the week …” Mark 16:1, 9

This describes the day of Jesus’ resurrection on the first day of the week. In the Good News Translation, which chose plainer expressions, the same verse is written as “After Jesus rose from death early on Sunday.” Since the first day of the week is Sunday, what day of the week is the Sabbath day that is the seventh day of the week?

The Sabbath day is definitely Saturday. And it says in verse 1, “When the Sabbath was over,” to describe the day when Jesus rose. I think this shows the Sabbath day was observed even in the time of Jesus as well.
Sister! When you learn one thing, you understand two things! The Sabbath day is very important to people who want to be saved. Do you know why?
Well, I’m not sure …
It’s because the Sabbath day is the day to confirm the relationship between God and us.

“You must observe my Sabbaths. This will be a sign between me and you for the generations to come, so you may know that I am the LORD, who makes you holy.” Exodus 31:13

When we keep the Sabbath day, we can know God. It is the day when greater blessings than anything else are promised. That’s why Jesus told us to remember the Sabbath day until the end.

“Pray that your flight will not take place in winter or on the Sabbath.” Matthew 24:20

Oh, now I get it! I wasn’t aware that the Sabbath day is this important.
God must be very pleased to see you regard the promise between God and us as important. I hope you will continue to make right choices all the time and receive much blessing from God.
Thank you! I’m already excited because God will bless my soul to become holy through today’s Sabbath day service!
Sure. Then, shall we go and prepare for the service to be blessed?