Lev 21:16-23 is an interesting scripture. Now that temple worship has been set aside, it is not relevant to Christian life. Through the work of the cross, we can all enter the presence of God. However, the principle behind this passage is interesting.
The LORD said to Moses, "Say to Aaron: 'For the generations to come one of your descendants who has a defect may come near to offer the food of his God. No man who has any defect may come near: no man who is blind or lame, disfigured or deformed; no man with a crippled foot or hand, or who is hunchbacked or dwarfed, or who has any eye defect, or who has festering or running sores or damaged testicles. No descendant of Aaron the priest who has any defect is to come near to present the offerings made to the LORD by fire. He has a defect; he must not come near to offer the food of his God. He may eat the most holy food of his God, as well as the holy food; yet because of his defect, he must not go near the curtain or approach the altar, and so desecrate my sanctuary. I am the LORD, who makes them holy.
Many Christians believe that God uses their sickness and pain to make us holy. This passage blows that idea out of the water. Sickness and disease do not make people holy, they actually desecrate our body, the sanctuary of the Holy Spirit. Those who are sick and diseased can enjoy the blessings of God (holy food), but their sickness is not pleasing to him.
How can this be? The Bible teaches that sickness and disease are not sent by God, but are the works of the sin and the devil. Rather than seeing them as a gift from God, we should resist the works of the devil and learn to apply the cross to all the effects of sin. Yahweh Rapha is the God who heals. We urgently need the healing power of the cross.