Then the LORD said to Aaron: “You, your sons, and your relatives from the tribe of Levi will be held responsible for any offenses related to the sanctuary. But you and your sons alone will be held responsible for violations connected with the priesthood.
“Bring your relatives of the tribe of Levi—your ancestral tribe—to assist you and your sons as you perform the sacred duties in front of the Tabernacle of the Covenant. But as the Levites go about all their assigned duties at the Tabernacle, they must be careful not to go near any of the sacred objects or the altar. If they do, both you and they will die. The Levites must join you in fulfilling their responsibilities for the care and maintenance of the Tabernacle, but no unauthorized person may assist you.
“You yourselves must perform the sacred duties inside the sanctuary and at the altar. If you follow these instructions, the LORD’s anger will never again blaze against the people of Israel. I myself have chosen your fellow Levites from among the Israelites to be your special assistants. They are a gift to you, dedicated to the LORD for service in the Tabernacle. But you and your sons, the priests, must personally handle all the priestly rituals associated with the altar and with everything behind the inner curtain. I am giving you the priesthood as your special privilege of service. Any unauthorized person who comes too near the sanctuary will be put to death.” (Numbers 18:1-7)
Everyone has a job to do. Aaron and his descendents were the priests. They alone were allowed to perform the sacrifices. The tribe that they belonged to, the tribe of Levi, was given the responsibility to help them perform their duties. It was like the difference between the pilots who fly the airplanes, versus those who do maintenance, run the radar and man the radios. Only the pilots are actually allowed in the cockpits to fly the planes. So the priests alone were permitted in the holy place and most holy place when the sacrifices were performed. The priests alone killed the sacrificial animal and placed its meat on the altar. But all those involved were necessary and important. Without the support staff—the Levites—the sacrifices couldn’t have been conducted. Everyone involved was important and necessary.
Being on the front lines of worshipping God was a dangerous position: much like the pilots who fly into enemy territory. Those back at the base, like the Levites, had their own dangers to worry about.
Each and every person has a role to play for God. Only as we work together can the goal—the ultimate purpose—be achieved.