Mar 2:17 They that are whole have no need of the physician, but they that are sick: I came not to call the righteous, but sinners to repentance.
Alternative: The strong have no need of a healer, but the bad have. I set out not to summon those observant of the rules but those who err to change their minds.

In the narrative, Christ has healed three times at this point in Mark so his statement is perfectly in context with the action thus far.

Christ here divides humanity not once but twice.

He says some people are "whole" while others are "sick" or, in a more direct translation, "strong" and "bad." Interestingly, the Greek word used for "ill" here has much more the sense of "evil" than the world usually translated as "evil" in the Gospels. While the word can mean physically ill, this is not its usual use. The contrast with "strong" conveys the idea that evil is a form of weakness, a sickness of the spirit like the sicknesses of the mind, body, and relationships that Christ has already addressed in the three healings he has performed thus far.

He also says that some people are righteous while others are sinners, or, translating more directly, those observant of the rules and erroneous. In setting up this dual dichotomy, Christ tells us that observing the rules is the same as being strong, that is, that following the rules is difficult while ignoring the rules is easy. Virtue, in the sense of following the rules Christ is talking about, isn't easy nor is it mean to be. However, making bad choices and errors, though it may be easier, leads to a type of spiritual sickness.

While none of us are perfect, Christ does say that some people are strong and virtuous and were before his coming. He did not introduce virtue to the world but to spread it to those who are weak and sick. Strength is not a permanent condition for anyone. Even the strongest fall sick. Similarly, virtue is not a constant. Even the most virtuous people make mistakes. So we all need Christ. The question is one of when.

Christ would agree with those who say his teachings are for weaklings. The real question here is if those who think they are strong are truly the strong. The test Christ proposes is simple: do you obey God's rules or do you make mistakes. The honest will admit that they fall into the latter category as often as the former. Interestingly, those who accuse the religious of being weak are also those most likely to think of virtue itself as a weakness. Christ the healer would diagnose them to be among those that are the most ill and the most need of healing.

Letting Christ into our lives is an admission of weakness, and admission that we need Christ and healing. We may admit this only in times of need, but Christ can only help us if we recognize that we need help. Since we are drowning in a sea of illusion, we often don't recognize our need, but the need is always there, especially with those who least recognize it.

Note hear that the word translated throughout the Gospels as "kingdom" also means "rule" and "reign." When Christ talks about observing the rules, these are the rules he is talking about. "Observant of the rules" means not only that you keep the rules, but that you recognize what they are. This is the hardest task when talking about God's laws. Some of these laws are easy to recognize but others are subtle and mysterious. For example, it is not only easy but unavoidable to observe certain laws of nature, like gravity, in one sense, but observing what gravity really is and how it really works is very difficult. Everyone obeyed the law of gravity until Newton, but Newton was the first to really observe what that law was. The same is true for all of God's laws. You can obey them without really observing them and understanding them. It is the understanding that is difficult.

"They that are whole " is from ischuô (ischuo), which means "to be strong in body," "to be powerful," "to prevail," and "to be worth."

"Need" is from chreia (chreia ), which means "need," "want," "poverty," "a request of anecessity," "business," "military service," "a business affair," "employment," "familiarity," "intimacy," and "maxim."

"Physician" is from iatros (iatros), which means "one who heals," "physician," and "surgeon."

"Sick" is from kakos (kakos), which means "bad," "mean," "base," "ugly," "ill-born," "evil," "worthless," "sorry," "pernicious," and "ill."

"Come" is from erchomai, which means "to come" and "to go." It means "to set out" and "to arrive at." It is a little like we use the phrase "he is on his way,"or "to be under way," which can mean either that he is coming or going with no direct reference to the position of the speaker.

"Call," is from kaleô (kaleo), which means "call," "summon," "invite," "invoke," "call by name," and "demand."

"Righteous" is from dikaios (dikaios) which means "observant of rules," "observant of customs," and "observant of duty." Later it means "well-balanced," "impartial," and "just." In Matthew, it is first translated as "the just" and later always as "the righteous."

"Sinners" is from hamartôlos (hamartolos) which means "erroneous," and "of bad character."

"Repentance," is from metanoeô (metanoia), which literally means "to perceive afterward," "to perceive too late," "to change one's mind," "to change one's purpose," and "to repent."