Why did God give Israel all these services and sacrifices?
God gave Israel the services and sacrifices as part of the law to serve as a picture of the coming Redeemer and the plan of salvation. They were not empty religion; the tabernacle, priesthood, feasts, and offerings all pointed forward to the salvation we experience today.
Les teaches that the service of God began when God gave the tabernacle to Moses and then set up the priesthood with Aaron as high priest. The services included how the priests operated, how the tabernacle and later the temple were set up, how the sacrifices were offered, and the setting up of the feast days throughout Israel's religious calendar year. Les explains that all of this was part and parcel of the system of law, not merely the Ten Commandments. It was not just a bunch of religion with nothing behind it; the practice of the law that Israel enjoyed was a picture of the coming Redeemer and the plan of salvation as we experience it today.
Who are Israelites; to whom pertaineth the adoption, and the glory, and the covenants, and the giving of the law, and the service of God, and the promises;