According to Luke 5:12, this man was "full of leprosy." Luke is describing an individual who was in the last stages of the dreaded disease; his life was a living death. Though he might have lived many more years, they would have been filled with indescribable misery and loneliness. The leper believed in the power of Jesus and had no doubt that Jesus could heal him. However, he wondered if Jesus would be willing to use His power on one deemed so unworthy and unclean.
Jesus' compassion led Him to touch the man. It is possible that this leper had not experienced the kindness and love of human touch for years (cf. Lev. 13:45,46). Jesus could have healed him with words only, but He chose to touch him also. Some believe that since Jesus touched this leper, He was unclean until evening. Even if this was the case, that is not to say that Jesus committed sin. To be unclean under the Old Testament did not necessarily mean one had committed sin (e.g., Lev. 15:18ff). Jesus is just as compassionate today as He was then. He sympathizes with those who are lost in sin just as He did with this leper. If a person is not saved from sin today it is not because Jesus is unwilling but because that individual will not yield his life to the Lord.
At the very instant Jesus touched the leper and told him that He was willing to heal him, the man was cleansed.
Now here's the fascinating part of this narrative. Jesus then proceeded to strictly warn the man to "say nothing to anyone" (Mark 1:43,44). Why would Jesus do this? Why would Jesus want this miracle to be kept a secret? The reason why Jesus commanded this man's silence was to suppress the excitement that the telling of this miracle would generate. Jesus didn't want great crowds gathering about him merely for the purpose of witnessing more miracles!
Jesus then commanded the man to show himself to the priest. Although he was healed of his leprosy, the man was not legally clean until a priest declared him so. This man was required under the Mosaic law to make the offerings prescribed in Leviticus 14. There is no record as to whether or not he did this, although we know that he did not obey Jesus' first command, as Mark 1:45 indicates.
The leper was so elated that he couldn't refrain from telling everyone as to how he was cured. Undoubtedly, his intentions were good, but his disobedience to Christ's command shows the weakness in human nature in following one's desires or feelings rather than doing exactly as the Lord commands. This is perhaps mankind's greatest problem--doing what he wants instead of simply obeying God.
As a result of the man spreading the word about his healing, "Jesus could no longer openly enter the city" (Mark 1:45). Jesus was not physically unable to do so, but He evidently didn't feel that going back into the city was the best thing to do. Throughout His ministry, Jesus was constantly threatened by two things: (1) impatience in the multitude and (2) the envious malice of the religious leaders. Jesus did not desire to make either of these problems worse at this time, but the man who was formerly a leper caused both to increase. His disobedience prevented Jesus from completely fulfilling His purpose in visiting these villages (cf. 1:38). Let all learn this lesson well: disobedience, despite our best intentions, always hinders the work of Christ!
Jesus stayed outside of the cities in deserted places for the purpose of prayer (cf. Luke 5:16). His intent was never to be just a physical healer. He wanted to teach the people; He wanted to save their souls!
In closing, let me point out the irony of this passage for twenty-first century disciples. The healed leper was told to keep quiet and followers today are told to speak the message freely (cf. Matt. 28:19,20). The leper, tragically, did what he wanted; he spread his good news about Jesus freely. Today, many who are commanded to proclaim the good news choose to do what they want (i.e., remain silent). Let me say it again: disobedience always hinders the work of Christ!