The reason God commanded them to keep the Sabbath was to lead them to the temple, where God dwelt. God was in the temple, and it was in the temple that he forgave the sins of the Israelites. However, if people approached God recklessly, they were put to death. As a result, Aaron's two sons, Nadab and Abihu, also died.

Therefore, not only the Sabbath, but also all sacrifices such as the regular burnt offering and the Day of Atonement are important procedures for approaching God. The purpose of God's presence in the temple was to forgive the sins of Israel and to impute all their sins to the devil. Therefore, if you realize the principle of receiving the forgiveness of sins in the temple, you will be able to properly judge the issue of keeping the Sabbath and Sunday worship services. The principle of receiving the forgiveness of sins in the temple is simple. 

When one of the Israelites sinned, the people brought an animal (sheep, goat, or dove) to the priest to atone for the sin. When the sins of the people were transferred to the animal, all of the sins were transferred to the animal. The priest would sprinkle the blood of the dead animal on the temple for the sins of the people, and the sins of the animal would be transferred to the temple. 

[Leviticus 17:11] Life is in the blood, and I have given you the blood of animals to sacrifice in place of your own. 

Therefore, these sacrifices were made in the temple. They offered burnt offerings on a regular basis every day, and they offered the Sabbath and New Moon every week. And once a year, sacrifices like the Day of Atonement were offered. The problem, however, is that the temple was stained with blood because of these sacrifices, and this blood symbolizes the sins of those brought to the temple. So they offered a sin offering once a year, which was the Day of Atonement. God instituted the sin offering on the 10th of July according to the Jewish calendar. And on that day all the sins of the temple were temporarily transferred to the Most Holy. God was with the Ark of the Covenant in the Most Holy, where the Ten Commandments were placed as his throne. 

Every year on the Day of Atonement, July 10, the high priest removed Israel's sins (animal blood) from the Holy of Holies. He then transferred the sins of the Holy of Holies to a goat, which he sent to a demon named Azazel. In the end, he sent all of his sins to a demon named Azazel. 

[Leviticus 16:20~30] "When Aaron has finished making atonement for the Most Holy Place, the Tent of Meeting and the altar, he shall bring forward the live goat. He is to lay both hands on the head of the live goat and confess over it all the wickedness and rebellion of the Israelites--all their sins--and put them on the goat's head. He shall send the goat away into the desert in the care of a man appointed for the task. The goat will carry on itself all their sins to a solitary place; and the man shall release it in the desert. "Then Aaron is to go into the Tent of Meeting and take off the linen garments he put on before he entered the Most Holy Place, and he is to leave them there. He shall bathe himself with water in a holy place and put on his regular garments. Then he shall come out and sacrifice the burnt offering for himself and the burnt offering for the people, to make atonement for himself and for the people. He shall also burn the fat of the sin offering on the altar. "The man who releases the goat as a scapegoat must wash his clothes and bathe himself with water; afterward he may come into the camp. The bull and the goat for the sin offerings, whose blood was brought into the Most Holy Place to make atonement, must be taken outside the camp; their hides, flesh and offal are to be burned up. The man who burns them must wash his clothes and bathe himself with water; afterward he may come into the camp. "This is to be a lasting ordinance for you: On the tenth day of the seventh month you must deny yourselves and not do any work--whether native-born or an alien living among you- because on this day atonement will be made for you, to cleanse you. Then, before the LORD, you will be clean from all your sins. 

By offering sacrifices on the Day of Atonement, God temporarily transferred the sins of the people in the Holy Place to the Most Holy, and eventually to the goats. And the goat was sent to a demon named Asazel to die. Therefore, opening the door (veil) of the Holy of Holies means that all the sins of Israel will be forgiven and the devil represented by Azazel will be judged. But the Apostle Paul testified that all of these were a pattern and a shadow that Yehoshua would do. 

[Hebrews 8:5] But the tent where they serve is just a copy and a shadow of the real one in heaven. Before Moses made the tent, he was told, "Be sure to make it exactly like the pattern you were shown on the mountain!" 

The earthly temple was a shadow of what Yehoshua would accomplish in the heavenly temple, so everything that was done in the temple for the sins of the people was a picture of what Yehoshua would accomplish in the heavenly temple.

[Mark 10:45] For even the Son of Man did not come to be served, but to serve, and to give his life as a ransom for many." 

Yehoshua's sacrifice on the cross was a sacrifice to atone for the sins of all people and marked the beginning of the sacrifices of the new covenant. In addition, Jesus himself became the high priest of the heavenly temple, opening the door (veil) of the heavenly holy of holies and entering in. In this regard, the Bible testifies. 

[Hebrews 9:11~12] Christ came as High Priest of the good things here and now. He also entered a much better tabernacle, not made by man and not of this world. Then Christ entered the Holy of Holies once for all, and set us free from sin forever, by offering his own blood instead of the blood of goats and bulls. 

Joshua's ascension to heaven after his resurrection is conclusive proof that he entered the heavenly Holy of Holies. Since the earthly Holy of Holies is a type of the heavenly Holy of Holies, the actual Holy of Holies is in heaven. Therefore, only the high priest of heaven can ascend to heaven. Therefore, it is certain that Joshua is the high priest of the heavenly temple. When Yehoshua ascended to heaven and cast Satan out of heaven to earth, he showed that he fulfilled the prophecy of the Day of Atonement. Just as all the sins of the people were transferred to Satan on the Day of Atonement by the laying of hands on the goat that was to be sent to Azazel, so Yehoshua transferred all the sins to Satan and cast him down to earth.

[Revelation 12:9] and were thrown down to the earth. Yes, that old snake and his angels were thrown out of heaven! That snake, who fools everyone on earth, is known as the devil and Satan. 

Yehoshua's sacrifice on the cross was a picture of the New Covenant sacrifices offered in the heavenly temple. Yehoshua entered the heavenly holy of holies bearing the sins of the people, imputed all their sins to Satan in heaven, and threw Satan to the ground. The casting of Satan to the ground fulfilled the prophecy that the goats sent to Azazel on the Day of Atonement would be driven into the wilderness. The prophecy of the Day of Atonement in the earthly temple was fulfilled when Satan was cast out. Thus, the sacrifices that atone for sin, such as the Sabbath and Sunday services, no longer needed to be kept. 

[Hebrews 10:18] After our sins are forgiven, we no longer have to offer sacrifices. 

Those who claim that it is right to keep the Sabbath and Sunday worship are making Yehoshua' sacrifice on the cross in vain.