Matthew 9:9, 13 As Jesus passed on from there, he saw a man called Matthew sitting at the tax office; and he said to him, "Follow me." And he rose and followed him. . . . Go and learn what this means, I desire mercy, and not sacrifice.' For I came not to call the righteous, but sinners."
Jesus called Matthew, and Matthew left everything and followed him. So what's important? That Matthew left everything? That Matthew followed? Its easy to focus on these things, because they look like things we can do - and if there is anything most people like to hear about. it is what we can do - for if we do something, then we can feel worthy, there is something we can claim credit for. The problem is that in the scope of things, what we do is really not important.
What we do is not important, because its not what we do that gets us to heaven, but what God has done in Christ. Anytime the focus is on what we do - I repented - I turned from sin - I did good works - even, I followed - whenever the focus is on what we do - there is one thing we can be certain of - and that is we are guilty of idolatry, for we are stealing the glory that belongs to God and keeping it for ourselves. That's not easy to hear - but it is often the nature of idolatry, that the other god is me, myself and I.
So what is important? Its not what we do, but what Jesus does - Jesus calls, Jesus invites. Jesus invitations shows us on the one hand that something is missing from our lives, and offers the promise to fill our lives, given them purpose, and provide for our needs. Jesus calls and Jesus invites, but he is not calling the righteous - Jesus is calling sinners. And that's the problem - our pride often gets in the way - we don't want to admit that we are poor miserable sinners. Jesus calls, and the chief thing that stand in the way is sinful human pride - even if we cannot save ourselves, we would at least like to claim that our response mattered, as though it contributed something.
That is the problem of the Pharisees, and they didn't die out along time ago - for every time we trust in a righteousness that is based on what we have done, we find ourselves in the company of the Pharisees. Every time we are troubled to see Jesus, our his disciples in the company of sinners, that is the jealousy of the Pharisees. You might not think you are a Pharisee, so here is a test - listen to yourself as you talk about your relationship with God - do you hear yourself using the language of sacrifice? Little things, like - I would have enjoyed sleeping in, but I got up and went to church - I had a lot of homework, but I still learned my memory work.
Sacrifice is the way we think we can pay our debts, even if we can't earn forgiveness for our sins, we look at our sacrifices as at least paying God back in part - something to, as it were, make us deserving of God's mercy.
But mercy is always unearned and undeserved - we can't give this unless God first gives mercy to us - unless we experience God's love in Christ - and then - and then mercy and love flow not from us, but from God working through us bring the good news of salvation into all the world.