Your Need - God's Desire

Now it happened, as Jesus sat at the table in the house, that behold, many tax collectors and sinners came and sat down with Him and His disciples. And when the Pharisees saw it, they said to His disciples, “Why does your Teacher eat with tax collectors and sinners?”
When Jesus heard that, He said to them, “Those who are well have no need of a physician, but those who are sick. But go and learn what this means: ‘I desire mercy and not sacrifice.’ For I did not come to call the righteous, but sinners, to repentance.”
Matthew 9:10–13 (NKJV)

Jesus teaches a short but pointed lesson upon this occasion. His popularity is still on the rise, and upon the call of Matthew to follow him, he is found to keep company with some of the most negatively viewed people in society at that time - tax collectors and sinners. Its important to note that the "sinner" designation did not just mean someone who committed sins, but one who was not living under the law. In some cases, a job that kept one ceremonially unclean would classify someone as a "sinner." But it could be the equivalent of being "unchurched" in modern society. It might not be that they were doing anything especially bad according the standards of mankind, but they also weren't trying to live adhere to the religion of the Old Testament.

Gentiles were considered sinners by default. Paul illustrates this perspective when writing to the Galatians he says, "We who are Jews by nature, and not sinners of the Gentiles" (Galatians 2:15). And Pharisaic Judaism created a difficult and sometimes impossible barrier to religious life. Jesus said, "For they bind heavy burdens, hard to bear, and lay them on men’s shoulders; but they themselves will not move them with one of their fingers" (Matthew 23:4).

Tax collectors were considered unpatriotic. That is not to say they religious scruples weren't in question. For those who claimed they were looking for God's coming Kingdom, to serve the treasure of the unpopular Roman occupiers was an affront on God. This is illustrated in the attempt to trap Jesus with the question if one should even pay taxes to Caesar.
"Tell us, therefore, what do You think? Is it lawful to pay taxes to Caesar, or not?" But Jesus perceived their wickedness, and said, “Why do you test Me, you hypocrites?..." - Matthew 22:17–19a (NKJV) 

But these that the religious of their world had given up on actually responded to Jesus' message, while those who were the most educated and seemingly godly rejected it. Why? Because they knew they were "sick." They had no errant presumption of righteousness. They were sinners, everyone knew. They were collecting taxes for the enemy of Gods Kingdom. They had no hope in the Legalistic traditional religion of the Pharisees. They had been shut out, or perhaps had just given up.

Because they knew they were in need, they were willing to turn to Jesus for that need. And while the met the icy stares of the Pharisees' judgment and rejection, Jesus reached out to them with mercy.

This is the model. This is the mission. This is the message. The self-righteous have convinced themselves they are healthy. But the Great Physicican only appeals to the "sick."

Why Not You?

We disqualify ourselves from God's service for many reasons. Our past. Our inadequacies. Our challenging circumstances. "Yes, I'm willing to serve, Lord! But alas, I cannot!" But is this accurate? Has God made a mistake in choosing you for service? We know better than that. God has chosen us all to serve, and has made it possible for each of us to serve in just the way He has chosen.

Credibility

Exodus 4:1–9 (NKJV)  
Then Moses answered and said, “But suppose they will not believe me or listen to my voice; suppose they say, ‘The Lord has not appeared to you.’ ” So the Lord said to him, “What is that in your hand?” He said, “A rod.” And He said, “Cast it on the ground.” So he cast it on the ground, and it became a serpent; and Moses fled from it. Then the Lord said to Moses, “Reach out your hand and take it by the tail” (and he reached out his hand and caught it, and it became a rod in his hand), “that they may believe that the Lord God of their fathers, the God of Abraham, the God of Isaac, and the God of Jacob, has appeared to you.” Furthermore the Lord said to him, “Now put your hand in your bosom.” And he put his hand in his bosom, and when he took it out, behold, his hand was leprous, like snow. And He said, “Put your hand in your bosom again.” So he put his hand in his bosom again, and drew it out of his bosom, and behold, it was restored like his other flesh. “Then it will be, if they do not believe you, nor heed the message of the first sign, that they may believe the message of the latter sign. And it shall be, if they do not believe even these two signs, or listen to your voice, that you shall take water from the river and pour it on the dry land. The water which you take from the river will become blood on the dry land.”

Ability

Exodus 4:10–12 (NKJV)  
Then Moses said to the Lord, “O my Lord, I am not eloquent, neither before nor since You have spoken to Your servant; but I am slow of speech and slow of tongue.” So the Lord said to him, “Who has made man’s mouth? Or who makes the mute, the deaf, the seeing, or the blind? Have not I, the Lord? Now therefore, go, and I will be with your mouth and teach you what you shall say.”

Alternative

Exodus 4:13–17 (NKJV)
But he said, “O my Lord, please send by the hand of whomever else You may send.” So the anger of the Lord was kindled against Moses, and He said: “Is not Aaron the Levite your brother? I know that he can speak well. And look, he is also coming out to meet you. When he sees you, he will be glad in his heart. Now you shall speak to him and put the words in his mouth. And I will be with your mouth and with his mouth, and I will teach you what you shall do. So he shall be your spokesman to the people. And he himself shall be as a mouth for you, and you shall be to him as God. And you shall take this rod in your hand, with which you shall do the signs.”