Leviticus 13:2 says, “When a man shall have in the skin of his flesh a rising, a scab, or bright spot, and it be in the skin of his flesh like the plague of leprosy; then he shall be brought unto Aaron the priest, or unto one of his sons the priests...”
Leprosy is an infectious disease that causes severe skin sores and nerve damage especially in the arms and legs. It starts small and then spreads. It was a dreaded disease and resulted in the afflicted being outcast (Num. 5:2).
Sin and false doctrine are likened to leprosy and leaven in the Bible (Gal. 5:9). Sin usually starts small (James 1:14-15). There is a temptation to hide leprosy when it starts, just like we tend to hide our sins (Prov. 28:13). The leper is to be brought to the priest like we need to go to Jesus (1st John 1:9).
When leprosy spreads (v. 7), the sensory nerves can be damaged, causing the leper to feel no pain. The same can be true with sin when your “conscience is seared” (1st Tim. 4:2). The “leprous man” is infectious (v. 44-46); likewise, sin often spreads to others (Lk 17:1-4). Therefore, the leper was to be separated from the congregation, and so is the sinner under certain circumstances (1st Cor. 5:13). Leprosy can cause death, and so can sin (Rom 8:12-13).
The bacteria that causes leprosy progresses very slowly; symptoms vary and don't usually start immediately. The consequences of sin are very similar. They don’t usually manifest themselves right away (Ps. 1:1). Leprous people with peripheral nerve damage may have muscle weakness that can result in deformities, paralysis, and even blindness. The effects of sin are very similar: they adversely affect your heart, mind, body, spirit, and soul.
Consider David when he committed adultery with Bathsheba (2nd Sam. 11:1-17): there was a desire, then deception, disobedience, and eventually death. Leprosy’s physical toll typifies the spiritual toll of sin – it can eat you away until you die (1st John 5:16-17).
Pastor Melito Barrera (Berean Bible Baptist Church of Chula Vista, California)