The call of Jesus is a strange one
Jesus calls Levi/Matthew to follow Him (Mark 2:13-17). And later he becomes one of Jesus' top men. What an absolutely bizarre choice on Jesus' part. After all, Levi was a tax collector, and tax collectors were the most despised men in Galilee (they're not well-liked today, for that matter). Politically, they were seen as traitors (collaborators with the Romans). Ethically, they were corrupt (known for extortion and charging whatever they felt like to make a buck). Religiously, they were unclean (they worked for, and spent time with Gentiles). Not the kind of person you'd expect Jesus to build a kingdom with. And yet, that's exactly what He does.
When you read this story, you immediately have to conclude that Jesus sees things differently than we do. We see Levi the tax collector. Jesus sees the potential for Matthew the Gospel writer, the great evangelist and martyr. Jesus saw a man, not a category, and He knew what that man could become. How many people have I given up on, because they seem too far away from God?
We also see that the initiative in this call lies squarely with Jesus. Perhaps they have had other interactions, but Mark clearly wants us to know that Jesus is approaching Levi, not the other way around. So it is with all His disciples (John 15:16). As John Calvin says, "Jesus teaches the calling of us all depends not on the merits of our own righteousness, but on his sheer generosity." Both comforting and humbling all at once. The gospel is like that.
The call of Levi tells us also that the gospel is a call to Jesus. "Follow me" He says. At the end of the day, this makes Christianity different from any other religion. At the center of Christianity is NOT a philosophy to be studied, a social ethic to be worked out, nor a list of rules to be obeyed. All those elements are there. But at the CENTER of Christianity is a Person to be followed. This is the call of the gospel - "Follow Jesus."