Leviticus 21:12
Neither shall he go out of the sanctuary, nor profane the sanctuary of his God; for the crown of the anointing oil of his God is upon him: I am the LORD. Neither shall he go out of the sanctuary, nor profane the sanctuary of his God; for the crown of the anointing oil of his God is upon him: I am the LORD.
Those who ministered in the sanctuary were required to be pure and holy, as set forth in Leviticus 21:6-23, because their work brought them into close connection with God. That closeness demanded undivided consecration, so that nothing impure or defiling could be associated with the sanctuary service. God remains just as holy and particular now, and therefore those who minister for Jesus must be holy, pure, and without blemish.